151
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Barron C, Migliaccio AR, Migliaccio G, Jiang Y, Adamson JW, Ottolenghi S. Alternatively spliced mRNAs encoding soluble isoforms of the erythropoietin receptor in murine cell lines and bone marrow. Gene 1994; 147:263-8. [PMID: 7926812 DOI: 10.1016/0378-1119(94)90078-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
32D Epo and 32D GM cells are subclones of the murine 32D cell line which are selectively dependent for proliferation and survival on erythropoietin (Epo) or granulocyte/macrophage colony-stimulating factor (GM-CSF), respectively. 32D GM cells were previously shown to express significant levels of the Epo receptor mRNA and protein which was retained intracellularly and did not appear on the cell surface. We have now analyzed the EpoR mRNA from the 32D GM line, using PCR followed by direct sequencing. Several alternatively spliced products were detected. In some molecules, intron 5 (I5) or part of I6 or both were retained. Retention of I5 results in a mRNA potentially encoding an almost complete extracellular domain, while retention of I6 gives rise to a mRNA encoding the complete extracellular and transmembrane domains. A different type of splicing results in the loss of exon 5 (E5), giving rise to a sequence encoding a truncated extracellular domain. These alternatively spliced sequences are differentially represented in 32D Epo versus 32D GM cells. All are additionally present in normal bone marrow cells. Apart from these alternatively spliced EpoR RNAs, no other abnormalities were detected in EpoR RNA from 32D GM cells that could account for the intracellular retention of EpoR in the non-erythroid subclones of 32D.
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Affiliation(s)
- C Barron
- Dipartimento di Genetica e di Biologia dei Microrganismi, Università degli Studi di Milano, Italy
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152
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Cytoplasmic tail deletion of T cell receptor (TCR) beta-chain results in its surface expression as glycosylphosphatidylinositol-anchored polypeptide on mature T cells in the absence of TCR-alpha. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31710-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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153
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Velan B, Kronman C, Flashner Y, Shafferman A. Reversal of signal-mediated cellular retention by subunit assembly of human acetylcholinesterase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31705-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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154
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Abstract
Transmembrane alpha-helices can associate with one another in lipid bilayers. This association is important in the folding and oligomerization of many integral membrane proteins, and may also play a role in their function. The interactions between helices may be highly specific or relatively non-specific, and their roles may differ accordingly. These two cases are discussed.
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Affiliation(s)
- M A Lemmon
- Department of Pharmacology, New York University Medical Center, NY 10016
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155
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Love PE, Shores EW, Lee EJ, Grinberg A, Munitz TI, Westphal H, Singer A. Differential effects of zeta and eta transgenes on early alpha/beta T cell development. J Exp Med 1994; 179:1485-94. [PMID: 8163933 PMCID: PMC2191483 DOI: 10.1084/jem.179.5.1485] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The zeta-family dimers (zeta, eta, and gamma) are a group of structurally and functionally related proteins that are expressed in developing thymocytes and function as signal transducing subunits of the T cell antigen receptor (TCR) and certain Ig Fc receptors. Zeta, eta, and gamma each contain one or more copies of a conserved tyrosine-based activation motif (TAM) that is known to be required for signal transduction. To examine the developmental importance of multiple or individual TAM elements we generated transgenic mice that express: (a) full-length (FL) zeta-chain (3 TAMs); (b) eta-chain, a naturally occurring variant of zeta that is derived from alternative splicing (2 TAMs); or (c) truncated zeta-chain (CT108; 1 TAM), under the control of the human CD2 promoter and regulatory elements. Unexpectedly, we found that overexpression of the FL zeta chain caused premature termination of RAG-1 and RAG-2 expression, prevented productive rearrangement of the TCR-alpha and TCR-beta genes and blocked entry of thymocytes into the CD4/CD8 developmental pathway. In contrast, we found that overexpression of eta or CT108 had no effect on normal thymocyte maturation. These results suggest that an early signaling pathway exists in precursor TCR- thymocytes that can regulate RAG-1 and RAG-2 expression and is differentially responsive to individual members of the zeta-family dimers.
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MESH Headings
- Animals
- CD3 Complex/genetics
- Cell Differentiation
- Cloning, Molecular
- Membrane Proteins/genetics
- Mice
- Mice, Transgenic
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Signal Transduction
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- Thymus Gland/cytology
- Thymus Gland/embryology
- Tyrosine/metabolism
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Affiliation(s)
- P E Love
- Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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156
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Abstract
The membrane-spanning portions of many integral membrane proteins consist of one or a number of transmembrane α-helices, which are expected to be independently stable on thermodynamic grounds. Side-by-side interactions between these transmembrane α-helices are important in the folding and assembly of such integral membrane proteins and their complexes. In considering the contribution of these helix–helix interactions to membrane protein folding and oligomerization, a distinction between the energetics and specificity should be recognized. A number of contributions to the energetics of transmembrane helix association within the lipid bilayer will be relatively non-specific, including those resulting from charge–charge interactions and lipid–packing effects. Specificity (and part of the energy) in transmembrane α-helix association, however, appears to rely mainly upon a detailed stereochemical fit between sets of dynamically accessible states of particular helices. In some cases, these interactions are mediated in part by prosthetic groups.
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Affiliation(s)
- M A Lemmon
- Department of Pharmacology, New York University Medical Center, NY 10016
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157
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Renard S, Lingueglia E, Voilley N, Lazdunski M, Barbry P. Biochemical analysis of the membrane topology of the amiloride-sensitive Na+ channel. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)99972-2] [Citation(s) in RCA: 172] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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158
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Einfeld DA, Hunter E. Expression of the TM protein of Rous sarcoma virus in the absence of SU shows that this domain is capable of oligomerization and intracellular transport. J Virol 1994; 68:2513-20. [PMID: 8139033 PMCID: PMC236729 DOI: 10.1128/jvi.68.4.2513-2520.1994] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The SU and TM subunits of the Rous sarcoma virus glycoprotein, which are derived from a single polypeptide precursor, have been expressed independently with a simian virus 40 vector. The TM protein retains the ability to form an oligomer which resembles the TM oligomer derived from the wild-type glycoprotein complex present in virions. Oligomerization of the recombinant TM protein is more rapid than that observed for the intact glycoprotein expressed from the simian virus 40 vector and is required for its transport out of the endoplasmic reticulum. Oligomeric TM is terminally glycosylated in the Golgi complex but is less stable than the intact wild-type protein and does not accumulate at the cell surface. The SU protein, in contrast, does not form detectable oligomers but is efficiently secreted into the culture medium. These observations suggest that the oligomerization domain of the Rous sarcoma virus glycoprotein lies in the TM protein and that it can function independently of SU.
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Affiliation(s)
- D A Einfeld
- Department of Microbiology, University of Alabama at Birmingham 35294
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159
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Manolios N, Kemp O, Li ZG. The T cell antigen receptor alpha and beta chains interact via distinct regions with CD3 chains. Eur J Immunol 1994; 24:84-92. [PMID: 8020575 DOI: 10.1002/eji.1830240114] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Selective pairwise interactions between CD3 chains and the clonotypic T cell antigen receptor (TCR)-alpha, -beta chains has recently been established. In this study, the region of interaction between clonotypic and CD3 chains involved with assembly was examined. To determine the site of protein interaction a variety of genetically altered TCR chains were constructed. These included: truncated proteins, lacking transmembrane and or cytosolic domains; chimeric proteins, in which extracellular, transmembrane or cytosolic domains were replaced with similar domains derived from either the Tac antigen or CD4; and point mutagenized TCR chains. COS-1 cells were transfected with cDNA, metabolically labeled, and immunoprecipitates analyzed using non-equilibrium pH gel electrophoresis (NEPHGE)-SDS/PAGE. The results demonstrated that assembly between TCR-alpha and TCR-beta chains occurred at the extracellular level. Assembly of the TCR-alpha chain with CD3-delta, and CD3-epsilon was localized to an eight-amino acid motif within the transmembrane domain of TCR-alpha. Site-specific mutations of the TCR-alpha charged residues within this motif (arginine, lysine) to leucine and similar point mutations of the transmembrane CD3-epsilon and CD3-delta charge groups resulted in the abrogation of assembly. In contrast, TCR-beta and CD3-epsilon binary complexes interacted via their extracellular domain. Analogous to TCR-alpha, the site of TCR-beta and CD3-delta assembly was at the transmembrane region. Despite multiple genetic manipulations on CD3-gamma and zeta these proteins failed to assemble with TCR-alpha. Similarly, there was no interaction between TCR-beta and zeta. These findings when coupled with the information on pairwise interactions and formation of higher order subcomplexes extend our model for the structure of the TCR complex.
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MESH Headings
- Animals
- CD3 Complex/chemistry
- CD3 Complex/metabolism
- DNA, Recombinant
- Electrophoresis, Gel, Two-Dimensional
- Precipitin Tests
- Receptor-CD3 Complex, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Recombinant Proteins/metabolism
- Transfection
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Affiliation(s)
- N Manolios
- Rheumatology Department, Royal North Shore Hospital, St. Leonards, Sydney, NSW, Australia
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160
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Gandy S, Greengard P. Processing of Alzheimer A beta-amyloid precursor protein: cell biology, regulation, and role in Alzheimer disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1994; 36:29-50. [PMID: 7822119 DOI: 10.1016/s0074-7742(08)60302-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- S Gandy
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York 10021
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161
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Barra RM, Fenjves ES, Taichman LB. Secretion of apolipoprotein E by basal cells in cultures of epidermal keratinocytes. J Invest Dermatol 1994; 102:61-6. [PMID: 8288912 DOI: 10.1111/1523-1747.ep12371733] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recently it has been shown that apolipoprotein E (apoE) secreted by keratinocytes in transplanted epidermal grafts reaches the systemic circulation. In this study we ask which cells in cultures of epidermal keratinocytes, basal or suprabasal, are the source of apoE. By fractionating disaggregated cultures in gradients of Ficoll400, the small nondifferentiated cells derived from the basal compartment were shown to be the source of apoE. The larger more differentiated cells derived from suprabasal layers could not be shown to contain or secrete apoE, although they did contain the apoE mRNA. Basal cells are the primary site for replication. However, analysis during growth in culture indicated that secretion did not correlate with cell replication but appeared to be linked to specific changes in metabolic activity of the basal cell compartment. Localization of apoE secretion to the basal compartment may provide a mechanism for lipid uptake and redistribution within the epidermis and may be viewed within the larger context of keratinocyte differentiation.
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Affiliation(s)
- R M Barra
- Department of Oral Biology and Pathology, School of Dental Medicine, State University of New York at Stony Brook 11794-8702
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162
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Studies of APP Biology: Analysis of APP Secretion and Characterization of an APP Homologue, APLP2. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/978-3-662-01135-5_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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163
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Chapter 3 Structural Requirements for Subunit Assembly of the Na, K-ATPase. CURRENT TOPICS IN MEMBRANES 1994. [DOI: 10.1016/s0070-2161(08)60453-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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164
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UytdeHaag FG, van Binnendijk RS, Kenter MJ, Osterhaus AD. Cytotoxic T lymphocyte responses against measles virus. Curr Top Microbiol Immunol 1994; 189:151-67. [PMID: 7924435 DOI: 10.1007/978-3-642-78530-6_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- F G UytdeHaag
- Department of Virology, Erasmus University Rotterdam, The Netherlands
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165
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Affiliation(s)
- G von Heijne
- Department of Molecular Biology, Karolinska Institute, Huddinge, Sweden
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166
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Rapid degradation of an unassembled immunoglobulin light chain is mediated by a serine protease and occurs in a pre-Golgi compartment. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74477-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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167
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Pieters J, Bakke O, Dobberstein B. The MHC class II-associated invariant chain contains two endosomal targeting signals within its cytoplasmic tail. J Cell Sci 1993; 106 ( Pt 3):831-46. [PMID: 8308066 DOI: 10.1242/jcs.106.3.831] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The oligomeric complex formed by major histocompatibility complex (MHC) class II alpha and beta chains and invariant chain (Ii) assembles in the endoplasmic reticulum and is then transported via the Golgi complex to compartments of the endocytic pathway. When Ii alone is expressed in CV1 cells it is sorted to endosomes. The Ii cytoplasmic tail has been found to be essential for targeting to these compartments. In order to characterize further the signals responsible for endosomal targeting, we have deleted various segments of the cytoplasmic tail. The Ii mutants were transiently expressed and the cellular location of the proteins was analyzed biochemically and morphologically. The cytoplasmic tail of Ii was found to contain two endosomal targeting sequences within its cytoplasmic tail; one targeting sequence was present within amino acid residues 12–29 and deletion of this segment revealed the presence of a second endosomal targeting sequence, located within the first 11 amino acid residues. The presence of a leucine-isoleucine pair at positions 7 and 8 within this sequence was found to be essential for endosomal targeting. In addition, the presence of this L-I motif lead to accumulation of Ii molecules in large endosomal vacuoles containing lysosomal marker proteins. Both wild type Ii and Ii mutant molecules containing only one endosomal targeting sequence were rapidly internalized from the plasma membrane. When the Ii cytoplasmic tail was fused to the membrane-spanning region of neuraminidase, a resident plasma membrane protein, the resulting chimera (INA) was found in endocytic compartments containing lysosomal marker proteins. Thus the cytoplasmic tail of Ii is sufficient for targeting to the endocytic/lysosomal pathway.
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Affiliation(s)
- J Pieters
- Cell Biology Programme, European Molecular Biology Laboratory Heidelberg, FRG
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168
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Hamrick M, Renaud K, Fambrough D. Assembly of the extracellular domain of the Na,K-ATPase beta subunit with the alpha subunit. Analysis of beta subunit chimeras and carboxyl-terminal deletions. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80535-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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169
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Ledford BE, Magor BG, Middleton DL, Miller RL, Wilson MR, Miller NW, Clem LW, Warr GW. Expression of a mouse-channel catfish chimeric IgM molecule in a mouse myeloma cell. Mol Immunol 1993; 30:1405-17. [PMID: 8232326 DOI: 10.1016/0161-5890(93)90102-h] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fusion genes encoding a murine VH domain and the constant region domains of the mu chain from the channel catfish, Ictalurus punctatus, were stably expressed in the lambda light chain producing mouse myeloma cell line J558L. Although the pathways of pre-mRNA processing for expression of membrane (micron and secreted (microsecond) forms of the mu chain differ between mammals and teleosts, mRNAs encoding both catfish micron and microsecond were correctly expressed in the mouse myeloma cells. The mouse-channel catfish chimeric mu chain polypeptide was able to associate covalently with the mouse lambda light chain and assemble, intracellularly, into polymers of covalent structure (microL)2-8 which resembled those seen with native catfish IgM. In contrast to native catfish IgM, the mouse-catfish chimeric IgM showed the property of binding strongly to protein A of Staphylococcus aureus. The mouse-channel catfish chimeric IgM was core-glycosylated, but did not contain terminal sialic acid. Secretion rates for the chimeric IgM were low, and the possibility could not be excluded that extracellular chimeric IgM was released from dead or dying cells. The reason(s) for the intracellular retention of the chimeric IgM (probably in the endoplasmic reticulum) are not known, but those mechanisms involving retention via cysteine residues were excluded.
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Affiliation(s)
- B E Ledford
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston 29425-2211
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170
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Young J, Kane L, Exley M, Wileman T. Regulation of selective protein degradation in the endoplasmic reticulum by redox potential. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36586-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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171
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Love PE, Shores EW, Johnson MD, Tremblay ML, Lee EJ, Grinberg A, Huang SP, Singer A, Westphal H. T cell development in mice that lack the zeta chain of the T cell antigen receptor complex. Science 1993; 261:918-21. [PMID: 7688481 DOI: 10.1126/science.7688481] [Citation(s) in RCA: 172] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The zeta subunit of the T cell antigen receptor complex is required for targeting nascent receptor complexes to the cell surface and for receptor-mediated signal transduction. To examine the significance of the zeta subunit in T cell development, mice deficient for zeta expression were generated by gene targeting. These zeta-/- mice had few CD4+CD8+ thymocytes, and the generation of CD4+ and CD8+ single positive T cells was impaired but not completely abrogated. Peripheral T cells were present but were unusual in that they expressed small amounts of CD5 and few T cell receptors. Thus, zeta chain expression influences thymocyte differentiation but is not absolutely required for the generation of single positive T cells.
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MESH Headings
- Animals
- Antigens, CD/analysis
- CD3 Complex/analysis
- CD4 Antigens/analysis
- CD5 Antigens
- CD8 Antigens/analysis
- Cell Differentiation
- Membrane Proteins/genetics
- Membrane Proteins/physiology
- Mice
- Mutation
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/physiology
- Receptors, Antigen, T-Cell, alpha-beta/analysis
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- Thymus Gland/cytology
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Affiliation(s)
- P E Love
- Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, National Institutes of Health (NIH), Bethesda, MD 20892
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172
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Vivier E, da Silva AJ, Ackerly M, Levine H, Rudd CE, Anderson P. Association of a 70-kDa tyrosine phosphoprotein with the CD16: zeta: gamma complex expressed in human natural killer cells. Eur J Immunol 1993; 23:1872-6. [PMID: 8344348 DOI: 10.1002/eji.1830230821] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The CD16: zeta: gamma receptor complex allows natural killer (NK) cells to recognize and eliminate antibody-coated target cells. Whereas the ectodomain of CD16 is the receptor for Fc gamma domains of immunoglobulins, disulfide-linked homo- and heterodimers composed of zeta and gamma are required for the cell surface expression, and signal transduction properties of the complex. Engagement of CD16 activates the tyrosine kinase pathway, which induces the tyrosine phosphorylation of several substrates, including the zeta subunit and the phospholipase C gamma-1 and gamma-2 isoforms. Here we show that CD16 stimulation of either peripheral blood NK cells, leukemic NK cells, or Jurkat transformants expressing a CD16: zeta: gamma receptor complex, results in the tyrosine phosphorylation of a 70 kDa zeta-associated protein (pp70). Similarly, a 70-kDa zeta-associated phosphoprotein in T cells has been shown to be a tyrosine kinase (ZAP-70). Peptide mapping analysis indicates that the 70-kDa zeta-associated phosphoproteins from T cells and NK cells are structurally indistinguishable. We conclude that the CD16: zeta: gamma complex may use a ZAP-70-related non-receptor tyrosine kinase, in the CD16 signaling cascade leading to NK cell activation.
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Affiliation(s)
- E Vivier
- Department of Pathology, Harvard Medical School, Boston, MA
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173
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Usami M, Yamao-Harigaya W, Maruyama K. The triplet of lysine residues (Lys724-Lys725-Lys726) of Alzheimer's amyloid precursor protein plays an important role in membrane anchorage and processing. J Neurochem 1993; 61:239-46. [PMID: 8515269 DOI: 10.1111/j.1471-4159.1993.tb03560.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
One of the pathological changes of Alzheimer's disease is the deposit of beta/A4 protein, which is derived from Alzheimer amyloid precursor protein (APP). In the secretory pathway, APP is cleaved at an internal region of beta/A4 protein by a hypothetical enzyme "secretase." Our previous study showed that the site of cleavage of APP by secretase is determined by the length from the membrane-spanning region. To investigate the role of the transmembrane region in APP secretion, we constructed the mutations of triplet lysine residues (Lys724-Lys725-Lys726), which are located just in the carboxyl region after the proposed membrane domain. The mutations were as follows: VVK, Val724-Val725-Lys726; LLI, Leu724-Leu725-Ile726; and EEE, Glu724-Glu725-Glu726. Wild-type APP and mutant APPs were expressed transiently in COS-1 cells by cDNA transfection. The hydrophobic mutant VVK and LLI were processed and secreted in a way similar to that of the wild-type APP, although the rate of secretion was decreased. The acidic mutant EEE was not secreted into medium. Proteinase K treatment and cell surface biotinylation of the COS-1 cells expressing APP revealed that APP was located in the plasma membrane with a short intracellular carboxyl region. However, EEE was completely digested by proteinase K treatment, which suggested that the whole residues of this mutant are located at the outer surface of the cell, including its proposed membrane domain and carboxyl region. This mutant was not cleaved at all by secretase. These findings suggested that the triplet lysine residues of AP after the predicted membrane spanning domain play an important role in the membrane anchorage.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Usami
- Department of Molecular Biology, Tokyo Institute of Psychiatry, Japan
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174
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Wileman T, Kane LP, Young J, Carson GR, Terhorst C. Associations between subunit ectodomains promote T cell antigen receptor assembly and protect against degradation in the ER. J Biophys Biochem Cytol 1993; 122:67-78. [PMID: 8314847 PMCID: PMC2119608 DOI: 10.1083/jcb.122.1.67] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The T cell antigen receptor (TCR) is an oligomeric protein complex made from at least six different integral membrane proteins (alpha beta gamma delta epsilon and zeta). The TCR is assembled in the ER of T cells, and correct assembly is required for transport to the cell surface. Single subunits and partial receptor complexes are retained in the ER where TCR alpha, beta, and CD3 delta chains are degraded selectively. The information required for the ER degradation of the TCR beta chain is confined to the membrane anchor of the protein (Wileman et al., 1990c; Bonifacino et al., 1990b). In this study we show that the rapid degradation of the TCR beta chain is inhibited when it assembles with single CD3 gamma, delta, or epsilon subunits in the ER, and have started to define the role played by transmembrane anchors, and receptor ectodomains, in the masking proteolytic targeting information. Acidic residues within the membrane spanning domains of CD3 subunits were essential for binding to the TCR beta chain. TCR beta chains and CD3 subunits therefore interact via transmembrane domains. However, when sites of binding were restricted to the membrane anchor of the TCR beta chain, stabilization by CD3 subunits was markedly reduced. Interactions between membrane spanning domains were not, therefore, sufficient for the protection of the beta chain from ER proteolysis. The presence of the C beta domain, containing the first 150 amino acids of the TCR ectodomain, greatly increased the stability of complexes formed in the ER. For assembly with CD3 epsilon, stability was further enhanced by the V beta amino acids. The results showed that the efficient neutralization of transmembrane proteolytic targeting information required associations between membrane spanning domains and the presence of receptor ectodomains. Interactions between receptor ectodomains may slow the dissociation of CD3 subunits from the beta chain and prolong the masking of transmembrane targeting information. In addition, the close proximity of TCR and CD3 ectodomains within the ER may provide steric protection from the action of proteases within the ER lumen.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- CHO Cells
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cloning, Molecular
- Cricetinae
- Endoplasmic Reticulum/metabolism
- Kinetics
- Macromolecular Substances
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Processing, Post-Translational
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/biosynthesis
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/metabolism
- T-Lymphocytes/metabolism
- Time Factors
- Transfection
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Affiliation(s)
- T Wileman
- Beth Israel Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215
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175
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Borst J, Brouns GS, de Vries E, Verschuren MC, Mason DY, van Dongen JJ. Antigen receptors on T and B lymphocytes: parallels in organization and function. Immunol Rev 1993; 132:49-84. [PMID: 8349297 DOI: 10.1111/j.1600-065x.1993.tb00837.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J Borst
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam
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176
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Shin J, Lee S, Strominger JL. Translocation of TCR alpha chains into the lumen of the endoplasmic reticulum and their degradation. Science 1993; 259:1901-4. [PMID: 8456316 DOI: 10.1126/science.8456316] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
After synthesis, the alpha chain of the T cell antigen receptor (TCR alpha) can form a complex with other TCR chains and move to the cell surface, or TCR alpha can undergo degradation in the endoplasmic reticulum (ER) if it remains unassembled. The mechanism of translocation and degradation in the ER is unclear. It was found that the putative transmembrane region of TCR alpha (alpha tm) was incompetent on its own to act as a transmembrane region. Molecules that contained alpha tm were translocated into the ER lumen and then underwent either rapid degradation or secretion, depending on the sequence of the cytoplasmic domain. A specific signal for ER degradation within alpha tm does not appear to be present.
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Affiliation(s)
- J Shin
- Division of Tumor Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115
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177
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Lankford S, Cosson P, Bonifacino J, Klausner R. Transmembrane domain length affects charge-mediated retention and degradation of proteins within the endoplasmic reticulum. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53469-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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178
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Humphrey JS, Peters PJ, Yuan LC, Bonifacino JS. Localization of TGN38 to the trans-Golgi network: involvement of a cytoplasmic tyrosine-containing sequence. J Cell Biol 1993; 120:1123-35. [PMID: 8436587 PMCID: PMC2119736 DOI: 10.1083/jcb.120.5.1123] [Citation(s) in RCA: 211] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Protein localization to the TGN was investigated by examining the subcellular distribution of chimeric proteins in which the cytoplasmic and/or transmembrane domains of the TGN protein, TGN38, were substituted for the analogous domains of the plasma membrane protein, Tac. Using immunofluorescence and immunoelectron microscopy, the COOH-terminal cytoplasmic domain of TGN38 was found to be sufficient for localization of the chimeric proteins to the TGN. Deletion analysis identified an 11-amino acid segment containing the critical sequence, YQRL, as being sufficient for TGN localization. TGN localization was abrogated by mutation of the tyrosine or leucine residues in this sequence to alanine, or of the arginine residue to aspartate. In addition to specifying TGN localization, the 11-amino acid segment was active as an internalization signal, although the property of internalization alone was insufficient to confer TGN localization. Overexpression of chimeric proteins containing TGN localization determinants resulted in their detection at the plasma membrane and in intracellular vesicles, and abolished detection of endogenous TGN38. These results suggest that discrete cytoplasmic determinants can mediate protein localization to the TGN, and reveal a novel role for tyrosine-based motifs in this process.
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Affiliation(s)
- J S Humphrey
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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179
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Smith S, Blobel G. The first membrane spanning region of the lamin B receptor is sufficient for sorting to the inner nuclear membrane. J Cell Biol 1993; 120:631-7. [PMID: 8381121 PMCID: PMC2119546 DOI: 10.1083/jcb.120.3.631] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The lamin B receptor (LBR) is a polytopic integral membrane protein localized exclusively in the inner nuclear membrane domain of the nuclear envelope. Its cDNA deduced primary structure consists of a highly charged amino-terminal domain of 205 residues that faces the nucleoplasm followed by a hydrophobic domain with eight potential transmembrane segments. To identify determinants that sort LBR from its site of integration (RER and outer nuclear membrane) to the inner nuclear membrane, we prepared full-length, truncated, and chimeric cDNA constructs of chick LBR, transfected these into mammalian cells and detected the expressed protein by immunofluorescence microscopy using appropriate antibodies. Surprisingly, we found that the determinants for sorting of LBR to the inner nuclear membrane reside in a region comprising its first transmembrane sequence plus flanking residues on either side. The other transmembrane regions as well as the nucleoplasmic domain are not required for sorting. We propose that the first transmembrane segment of LBR interacts specifically with another transmembrane segment and consider several mechanisms by which such specific interaction could result in sorting to the inner nuclear membrane.
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Affiliation(s)
- S Smith
- Laboratory of Cell Biology, Howard Hughes Medical Institute, Rockefeller University, New York 10021
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180
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Bennett J, Kolodziej M, Vilaire G, Poncz M. Determinants of the intracellular fate of truncated forms of the platelet glycoproteins IIb and IIIa. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53733-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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181
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Briesewitz R, Epstein M, Marcantonio E. Expression of native and truncated forms of the human integrin alpha 1 subunit. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53871-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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182
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Affiliation(s)
- A Fra
- Department of Biology and Technology Research, San Raffaele, Milan, Italy
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183
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Davis RA. The endoplasmic reticulum is the site of lipoprotein assembly and regulation of secretion. Subcell Biochem 1993; 21:169-87. [PMID: 8256265 DOI: 10.1007/978-1-4615-2912-5_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- R A Davis
- Department of Biology, San Diego State University, California 92182
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184
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Omura F, Otsu M, Yoshimori T, Tashiro Y, Kikuchi M. Non-lysosomal degradation of misfolded human lysozymes with and without an asparagine-linked glycosylation site. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:591-9. [PMID: 1459141 DOI: 10.1111/j.1432-1033.1992.tb17459.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human lysozyme is a monomeric secretory protein composed of 130 amino acid residues, with four intramolecular disulfide bonds and no oligosaccharides. In this study, a mutant protein, [Ala128] lysozyme, which cannot fold because it lacks a disulfide bond, Cys6-Cys128, was expressed in mouse fibroblasts and was found to be mostly degraded in the cells, whereas the control wild-type lysozyme was quantitatively secreted into the media. The degradation of [Ala128]lysozyme was independent of the transport from the endoplasmic reticulum to the Golgi apparatus. The degradation was greatly inhibited by incubation of cells at 15 degrees C, but was minimally affected by treatment of cells with the lysosomotropic agent, chloroquine, implying a non-lysosomal process. Additional mutations (Gly48-->Ser or Met29-->Thr) were created to make asparagine-linked (N-linked) glycosylation site in the [Ala128]lysozyme, and the resultant double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were analyzed with respect to their intracellular degradation. These mutant proteins were susceptible to N-linked glycosylation, and were degraded in a similar manner to that of [Ala128] lysozyme, except that the onset of degradation of [Ser48, Ala128]lysozyme and [Thr29, Ala128] lysozyme, but not of [Ala128]lysozyme, was preceded by a lag period of up to 60 min. Furthermore, the degradative double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were glycosylated post-translationally as well as co-translationally. These observations suggest that there is some interaction between the mechanisms of glycosylation and degradation.
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Affiliation(s)
- F Omura
- Protein Engineering Research Institute, Osaka, Japan
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185
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Urade R, Kito M. Inhibition by acidic phospholipids of protein degradation by ER-60 protease, a novel cysteine protease, of endoplasmic reticulum. FEBS Lett 1992; 312:83-6. [PMID: 1330685 DOI: 10.1016/0014-5793(92)81415-i] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A protein (ER60) with sequence similarity to phosphoinositide-specific phospholipase C-alpha purified from rat liver endoplasmic reticulum (ER) degraded ER resident proteins and is really a protease [(1992) J. Biol. Chem. 265, 15152-15159]. Therefore, ER60 is called ER-60 protease. We now show that negatively charged phospholipids, phosphatidylinositol, phosphatidylinositol 4,5-bisphosphate and phosphatidylserine inhibit ER protein degradation by ER-60 protease. Phosphatidylcholine and phosphatidylethanolamine show no effect on the activity of ER-60 protease. With the use of protease inhibitors, ER-60 protease is shown to be a novel cysteine protease distinct from those of the cytosol and lysosomes.
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Affiliation(s)
- R Urade
- Research Institute for Food Science, Kyoto University, Japan
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186
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Vertel BM, Walters LM, Mills D. Subcompartments of the endoplasmic reticulum. SEMINARS IN CELL BIOLOGY 1992; 3:325-41. [PMID: 1457776 DOI: 10.1016/1043-4682(92)90019-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The endoplasmic reticulum (ER) is the largest continuous endomembrane structure in the cytoplasm. It may be viewed as a series of unique subcompartments. In this review, we examine the rough ER, nuclear envelope and several smooth ER subcompartments. Consideration is given to the characteristic properties and functions of the ER and its domains, and to the formation and maintenance of subcompartments. Associations within the ER membrane bilayer, and with constituents of the cytoplasm and the ER lumen, contribute to the formation of domains and lead to the establishment of subcompartments that reflect specialized functions and vary according to the physiologic state and phenotype of the individual cell. Although the structural complexity of some ER subcompartments (such as the sarcoplasmic reticulum) is highly elaborate, the ER remains a dynamic organelle, subject to assembly and disassembly, capable of extensive remodelling and active in exchange with other organelles through mechanisms of membrane transport.
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Affiliation(s)
- B M Vertel
- Department of Cell Biology and Anatomy, Chicago Medical School, IL 60064
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187
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188
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Functional dissection of structural domains in the receptor for colony-stimulating factor-1. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42027-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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189
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Macintyre SS. Regulated export of a secretory protein from the ER of the hepatocyte: a specific binding site retaining C-reactive protein within the ER is downregulated during the acute phase response. J Biophys Biochem Cytol 1992; 118:253-65. [PMID: 1378445 PMCID: PMC2290050 DOI: 10.1083/jcb.118.2.253] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The half-time for secretion of the plasma protein C-reactive protein (CRP) by the hepatocyte decreases markedly in association with its increased synthesis during the acute phase response to tissue injury (Macintyre, S., D. Samols, and I. Kushner. 1985. J. Biol. Chem. 260:4169-4173). In studies in which subcellular fractions were prepared from cells incubated under pulse-chase conditions, CRP was found to be preferentially retained within the ER of normal hepatocytes, but secreted relatively efficiently in cells prepared from rabbits undergoing the acute phase response. On the basis of the detergent-dependency of specific binding of radiolabeled CRP, as well as EM visualization of biotinylated CRP identified with peroxidase-conjugated streptavidin, CRP was found to bind to the lumenal surface of permeabilized rough microsomes, while no binding was detected in Golgi fractions. As judged by both kinetic and equilibrium binding studies, rough microsomes from control rabbits were found to have two classes of specific binding sites for CRP; a high affinity site (Kd = 1 nM, Bmax = 1 pmol CRP/mg microsomal protein) as well as a much lower affinity (Kd = 140 nM) site. In contrast, only the lower affinity class was detected in microsomes isolated from rabbits undergoing the acute phase response. On nitrocellulose blots probed with radiolabeled CRP a 60-kD protein, distinct from BiP, was detected in extracts of rough microsomes isolated from control rabbits, but not in Golgi fractions or rough microsomes from stimulated animals. These findings correlate with previous observations of changes in secretion kinetics of CRP and are consistent with the hypothesis that the intracellular sorting of CRP could be rerouted by downregulation of a specific ER binding site during the acute phase response.
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Affiliation(s)
- S S Macintyre
- Case Western Reserve University, MetroHealth Medical Center, Cleveland, Ohio 44109-1998
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190
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Letourneur F, Klausner RD. A novel di-leucine motif and a tyrosine-based motif independently mediate lysosomal targeting and endocytosis of CD3 chains. Cell 1992; 69:1143-57. [PMID: 1535555 DOI: 10.1016/0092-8674(92)90636-q] [Citation(s) in RCA: 450] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Partial complexes of the T cell antigen receptor lacking zeta chains are delivered to lysosomes. Chimeric proteins composed of the Tac antigen fused to the cytoplasmic domains of each CD3 chain has allowed the identification of lysosomal targeting sequences. Tac-gamma and Tac-delta chimeras are retained in the endoplasmic reticulum because of the presence of basic residues reminiscent of sequences responsible for the localization of endoplasmic reticulum resident proteins. Truncation of these retention motifs revealed lysosomal targeting of both Tac-gamma and delta chimeras. A di-leucine- and a tyrosine-based motif are individually sufficient to induce both endocytosis and delivery to lysosomes of Tac. In contrast with chimeras containing only one of these motifs, the chimera containing both was predominantly delivered directly to lysosomes without going through the cell surface. These two sequences may represent two families of targeting motifs that determine the fate of proteins within the peripheral membrane system.
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Affiliation(s)
- F Letourneur
- Cell Biology and Metabolism Branch, National Institute of Child Health, Human Development, National Institutes of Health, Bethesda, Maryland 20892
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191
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Mallabiabarrena A, Fresno M, Alarcón B. An endoplasmic reticulum retention signal in the CD3 epsilon chain of the T-cell receptor. Nature 1992; 357:593-6. [PMID: 1535117 DOI: 10.1038/357593a0] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Isolated polypeptide chains of the T-cell antigen receptor complex are degraded or retained in the endoplasmic reticulum (ER). Assembly of the multisubunit complex allows the individual chains to escape retention in the ER and to be expressed on the cell surface. We engineered a series of deletions in the CD3 epsilon subunit of the human T-cell receptor in order to find the sequences responsible for its retention in the ER. Deletion of amino acids 171 to 180 in the cytosolic tail resulted in the cell-surface expression of the isolated chain. This sequence also promotes retention when it is appended to CD4, a plasma membrane protein. Mutagenesis of the 10-amino-acid CD3 epsilon sequence established that the tyrosine and serine residues are important for ER retention. This and other ER retention signals must be hidden when a complete T-cell receptor complex is assembled in order to allow its expression on the cell surface.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Differentiation, T-Lymphocyte/chemistry
- Antigens, Differentiation, T-Lymphocyte/genetics
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Base Sequence
- CD3 Complex
- Cell Membrane/immunology
- Endoplasmic Reticulum/immunology
- Gene Expression
- Golgi Apparatus/immunology
- Humans
- Mice
- Molecular Sequence Data
- Mutagenesis
- Polymerase Chain Reaction
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- Structure-Activity Relationship
- Transfection
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Affiliation(s)
- A Mallabiabarrena
- Centro de Biología Molecular, Universidad Autónoma de Madrid, CSIC, Spain
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192
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Substitution of the insulin receptor transmembrane domain with the c-neu/erbB2 transmembrane domain constitutively activates the insulin receptor kinase in vitro. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42298-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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193
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Engel I, Ottenhoff TH, Klausner RD. High-efficiency expression and solubilization of functional T cell antigen receptor heterodimers. Science 1992; 256:1318-21. [PMID: 1598575 DOI: 10.1126/science.1598575] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The T cell receptor (TCR) zeta chain was attached to the TCR alpha and beta extracellular domains to induce efficient expression of alpha beta heterodimers that can recognize complexes of antigen with major histocompatibility complex (MHC) molecules. Chimeric constructs expressed in RBL-2H3 cells were efficiently transported to the cell surface uniquely as disulfide-linked heterodimers. Transfectants were activated by specific antigen-MHC complexes, which demonstrated that the expressed alpha beta was functional and that CD3 was not required for antigen-MHC binding. Constructs with thrombin cleavage sites were efficiently cleaved to soluble disulfide-linked heterodimers. Thus, attachment of TCR zeta domains and protease cleavage sites to TCR alpha and beta induces expression of demonstrably functional heterodimers that can be solubilized.
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Affiliation(s)
- I Engel
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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194
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Hsu VW, Shah N, Klausner RD. A brefeldin A-like phenotype is induced by the overexpression of a human ERD-2-like protein, ELP-1. Cell 1992; 69:625-35. [PMID: 1316805 PMCID: PMC7133352 DOI: 10.1016/0092-8674(92)90226-3] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Brefeldin A (BFA) is a unique drug affecting the molecular mechanisms that regulate membrane traffic and organelle structure. BFA's ability to alter retrograde traffic from the Golgi to the endoplasmic reticulum (ER) led us to ask whether the ERD-2 retrieval receptor, proposed to return escaped ER resident proteins from the Golgi, might either interfere with or mimic the effects of the drug. When either human ERD-2 or a novel human homolog (referred to as ELP-1) is overexpressed in a variety of cell types, the effects are phenotypically indistinguishable from the addition of BFA. These include the redistribution of the Golgi coat protein, beta-COP, to the cytosol, the loss of the Golgi apparatus as a distinct organelle, the mixing of this organelle with the ER, the addition of complex oligosaccharides to resident ER glycoproteins, and the block of anterograde traffic. Thus, these receptors may provide signals that regulate retrograde traffic between the Golgi and the ER.
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Affiliation(s)
- V W Hsu
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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195
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Inoue S, Simoni R. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase and T cell receptor alpha subunit are differentially degraded in the endoplasmic reticulum. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50391-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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196
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Wong SH, Low SH, Hong W. The 17-residue transmembrane domain of beta-galactoside alpha 2,6-sialyltransferase is sufficient for Golgi retention. J Cell Biol 1992; 117:245-58. [PMID: 1560026 PMCID: PMC2289426 DOI: 10.1083/jcb.117.2.245] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
beta-Galactoside alpha 2,6-sialyltransferase (ST) is a type II integral membrane protein of the Golgi apparatus involved in the sialylation of N-linked glycans. A series of experiments has shown that the 17-residue transmembrane domain of ST is sufficient to confer localization to the Golgi apparatus when transferred to the corresponding region of a cell surface type II integral membrane protein. Lectin affinity chromatography of chimeric proteins bearing this 17-residue sequence suggests that these chimeric proteins are localized in the trans-Golgi cisternae and/or trans-Golgi network. Further experiments suggest that this 17-residue sequence functions as a retention signal for the Golgi apparatus.
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Affiliation(s)
- S H Wong
- Membrane Biology Laboratory, National University of Singapore
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197
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Gandy S, Greengard P. Amyloidogenesis in Alzheimer's disease: some possible therapeutic opportunities. Trends Pharmacol Sci 1992; 13:108-13. [PMID: 1574806 DOI: 10.1016/0165-6147(92)90039-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cerebral deposition of fibrils formed from the beta/A4 amyloid protein is an invariable feature of Alzheimer's disease. Evidence suggests that generation of such fibrils may be involved in the etiology of this disease, since mutations in the coding region of the beta/A4 amyloid precursor protein (APP) gene segregate with familial cerebral amyloidoses, including familial Alzheimer's disease. Transgenic models of cerebral amyloidosis have been produced, and some progress has been made in elucidating the cell biology of amyloidogenesis. For example, agents that alter protein phosphorylation are potent modulators of the expression and proteolytic processing of APP. Sam Gandy and Paul Greengard review these recent studies, and discuss those that may provide rational therapeutic opportunities.
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Affiliation(s)
- S Gandy
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021
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198
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PU.1 recruits a second nuclear factor to a site important for immunoglobulin kappa 3' enhancer activity. Mol Cell Biol 1992. [PMID: 1729611 DOI: 10.1128/mcb.12.1.368] [Citation(s) in RCA: 209] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
PU.1 is a B-cell- and macrophage-specific transcription factor. By an electrophoretic mobility shift assay and dimethyl sulfate methylation interference assays, we show that PU.1 binds to DNA sequences within the immunoglobulin kappa 3' enhancer (kappa E3'). Binding of PU.1 to the kappa E3' enhancer assists the binding of a second tissue-restricted factor, NF-EM5, to an adjacent site. Binding of NF-EM5 to kappa E3' DNA sequences requires protein-protein interaction with PU.1 as well as specific protein-DNA interactions. This is the first known instance of PU.1 interacting with another cellular protein. NF-EM5 does not cofractionate with PU.1, suggesting that it is a distinct protein and is not a posttranslational modification of PU.1. UV-crosslinking studies and elution from sodium dodecyl sulfate-polyacrylamide gels indicate that NF-EM5 is a protein of approximately 46 kDa. Site-directed mutagenesis studies of the PU.1- and EM5-binding sites indicate that these sites play important roles in kappa E3' enhancer activity. By using a series of PU.1 deletion constructs, we have identified a region in PU.1 that is necessary for interaction with NF-EM5. This segment encompasses a 43-amino-acid region with PEST sequence homology, i.e., one that is rich in proline (P), glutamic acid (E), serine (S), and threonine (T).
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199
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Le A, Ferrell GA, Dishon DS, Le QQ, Sifers RN. Soluble aggregates of the human PiZ alpha 1-antitrypsin variant are degraded within the endoplasmic reticulum by a mechanism sensitive to inhibitors of protein synthesis. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48397-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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200
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Lee AW. Signal transduction by the colony-stimulating factor-1 receptor; comparison to other receptor tyrosine kinases. CURRENT TOPICS IN CELLULAR REGULATION 1992; 32:73-181. [PMID: 1318184 DOI: 10.1016/b978-0-12-152832-4.50005-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- A W Lee
- Clinical Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
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