1
|
Lim B, Kydd L, Jaworski J. A Peptide-Lectin Fusion Strategy for Developing a Glycan Probe for Use in Various Assay Formats. CHEMOSENSORS 2019; 7. [PMID: 32793433 PMCID: PMC7423246 DOI: 10.3390/chemosensors7040055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
While nucleic acid and protein analysis approaches continue to see significant breakthroughs, analytical strategies for glycan determination have by comparison seen slower technological advances. Here we provide a strategy for glycan probe development using an engineered lectin fusion that can be incorporated into various common pathology lab assay formats including Western blot and agglutination assays. In this proof of concept, we use the natural lectin, Pseudomonas fluorescens agglutinin (PFA), capable of binding core Man alpha(1-3)-Man alpha(1-6)-Man units, where this lectin has previously been shown to bind to the glycans presented by the gp120 coat protein of (HIV) Human Immunodeficiency Virus. In our strategy, we engineered the lectin to possess a fusion of the biotin mimetic tag equence of amino acids V-S-H-P-Q-A-P-F. With the glycan receptive PFA directly linked to the biotin mimic, we could facilitate a probe for various standard clinical assay formats by virtue of coupling to streptavidin-HRP (horseradish peroxidase) or streptavidin beads for Western blot and agglutination assays respectively. We found the PFA fusion retained low nanomolar affinity for gp120 by ELISA (Enzyme Linked Immunosorbent Assay) and microscale thermophoresis. This probe engineering strategy proved effective in the relevant assay formats that may now allow detection for the presence of glycans containing the core Man alpha(1-3)-Man alpha(1-6)-Man units recognized by PFA.
Collapse
|
2
|
Stahl N, Baldwin MA, Hecker R, Pan KM, Burlingame AL, Prusiner SB. Glycosylinositol Phospholipid Anchors of the Scrapie and Cellular Prion Proteins Contain Sialic Acid. Biochemistry 2003; 31:5043-53. [PMID: 1350920 DOI: 10.1021/bi00136a600] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The only identified component of the scrapie prion is PrPSc, a glycosylinositol phospholipid (GPI)-linked protein that is derived from the cellular isoform (PrPC) by an as yet unknown posttranslational event. Analysis of the PrPSc GPI has revealed six different glycoforms, three of which are unprecedented. Two of the glycoforms contain N-acetylneuraminic acid, which has not been previously reported as a component of any GPI. The largest form of the GPI is proposed to have a glycan core consisting of Man alpha-Man alpha-Man-(NeuAc-Gal-GalNAc-)Man-GlcN-Ino. Identical PrPSc GPI structures were found for two distinct isolates or "strains" of prions which specify different incubation times, neuropathology, and PrPSc distribution in brains of Syrian hamsters. Limited analysis of the PrPC GPI reveals that it also has sialylated glycoforms, arguing that the presence of this monosaccharide does not distinguish PrPC from PrPSc.
Collapse
Affiliation(s)
- N Stahl
- Department of Neurology, University of California, San Francisco 94143
| | | | | | | | | | | |
Collapse
|
3
|
Chapter 12 Mass Spectrometry of Carbohydrates and Glycoconjugates. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0301-4770(08)60517-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
4
|
Mereyala HB, Guntha S. Disaccharides to inositol saccharides: synthesis of α-D-galactopyranosyl-D-myo-inositol derivatives from a methyl 4-O-(α-D-galactopyranosyl)-α-D-glucopyranoside derivative. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/p19930000841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
5
|
Preuss U, Schuler F, Peter-Katalinic J, Gunawan J, Egge H. Production of monoclonal antibodies against the purified glycosylphosphatidylinositol anchor of the variant surface glycoprotein from Trypanosoma brucei brucei. Arch Biochem Biophys 1991; 291:139-46. [PMID: 1834019 DOI: 10.1016/0003-9861(91)90116-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The glycosylphosphatidylinositol anchor (GPI) from the membrane form variant surface glycoprotein (mfVSG) of Trypanosoma brucei brucei was isolated and identified after radioactive labeling with [3H]myristic acid, by immunostaining on HPTLC with a polyclonal antibody directed against mfVSG and by negative ion laser desorption and fast atom bombardment mass spectrometry of the GPI anchor before and after peracetylation. For the production of monoclonal antibodies the purified GPI molecule was incorporated into liposomes and injected intrasplenically in BALB/c mice. After fusion with the myeloma cell line X63-Ag 8.653 hybridoma cells were cloned by single cell cloning. The secreted antibodies were characterized by ELISA, Ouchterlony immunodiffusion, and Western blot and used in first immunofluorescent studies.
Collapse
Affiliation(s)
- U Preuss
- Institut für Physiologische Chemie, Universität Bonn, Federal Republic of Germany
| | | | | | | | | |
Collapse
|
6
|
Sevlever D, Påhlsson P, Rosen G, Nilsson B, Londner MV. Structural analysis of a glycosylphosphatidylinositol glycolipid of Leishmania donovani. Glycoconj J 1991; 8:321-9. [PMID: 1668717 DOI: 10.1007/bf00731344] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A glycosylphosphatidylinositol (GPI) glycolipid antigen recognized by sera from patients with visceral leishmaniasis was isolated from Leishmania donovani promastigotes. The carbohydrate moiety was cleaved from the lipid part by digestion with specific phosphatidylinositol phospholipase C. After separation, structural analysis was carried out on the phosphorylated inositol oligosaccharide and the alkylacyl glycerol. The following major structures were found: [formula: see text] The presence of the conserved sequence Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcN-PI of glycosyl phosphatidylinositol protein anchors in this antigen may be consistent with a precursor role of Leishmania glycosyl phosphatidylinositol anchored proteins for this glycolipid.
Collapse
Affiliation(s)
- D Sevlever
- Department of Parasitology, Kuvin Centre for the Study of Infectious and Tropical Diseases, Hebrew University--Hadassah Medical School, Jerusalem, Israel
| | | | | | | | | |
Collapse
|
7
|
Determinants for glycophospholipid anchoring of the Saccharomyces cerevisiae GAS1 protein to the plasma membrane. Mol Cell Biol 1991. [PMID: 1824714 DOI: 10.1128/mcb.11.1.27] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 125-kDa glycoprotein exposed on the surface of Saccharomyces cerevisiae cells belongs to a class of eucaryotic membrane proteins anchored to the lipid bilayer by covalent linkage to an inositol-containing glycophospholipid. We have cloned the gene (GAS1) encoding the 125-kDa protein (Gas1p) and found that the function of Gas1p is not essential for cell viability. The nucleotide sequence of GAS1 predicts a 60-kDa polypeptide with a cleavable N-terminal signal sequence, potential sites for N- and O-linked glycosylation, and a C-terminal hydrophobic domain. Determination of the anchor attachment site revealed that the C-terminal hydrophobic domain of Gas1p is removed during anchor addition. However, this domain is essential for addition of the glycophospholipid anchor, since a truncated form of the protein failed to become attached to the membrane. Anchor addition was also abolished by a point mutation affecting the hydrophobic character of the C-terminal sequence. We conclude that glycophospholipid anchoring of Gas1p depends on the integrity of the C-terminal hydrophobic domain that is removed during anchor attachment.
Collapse
|
8
|
Murakata C, Ogawa T. Synthetic studies on glycophosphatidylinositol anchor: a highly efficient synthesis of glycobiosyl phosphatidylinositol through H-phosphonate approach. Tetrahedron Lett 1991. [DOI: 10.1016/s0040-4039(00)71229-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
9
|
|
10
|
Nuoffer C, Jenö P, Conzelmann A, Riezman H. Determinants for glycophospholipid anchoring of the Saccharomyces cerevisiae GAS1 protein to the plasma membrane. Mol Cell Biol 1991; 11:27-37. [PMID: 1824714 PMCID: PMC359581 DOI: 10.1128/mcb.11.1.27-37.1991] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A 125-kDa glycoprotein exposed on the surface of Saccharomyces cerevisiae cells belongs to a class of eucaryotic membrane proteins anchored to the lipid bilayer by covalent linkage to an inositol-containing glycophospholipid. We have cloned the gene (GAS1) encoding the 125-kDa protein (Gas1p) and found that the function of Gas1p is not essential for cell viability. The nucleotide sequence of GAS1 predicts a 60-kDa polypeptide with a cleavable N-terminal signal sequence, potential sites for N- and O-linked glycosylation, and a C-terminal hydrophobic domain. Determination of the anchor attachment site revealed that the C-terminal hydrophobic domain of Gas1p is removed during anchor addition. However, this domain is essential for addition of the glycophospholipid anchor, since a truncated form of the protein failed to become attached to the membrane. Anchor addition was also abolished by a point mutation affecting the hydrophobic character of the C-terminal sequence. We conclude that glycophospholipid anchoring of Gas1p depends on the integrity of the C-terminal hydrophobic domain that is removed during anchor attachment.
Collapse
Affiliation(s)
- C Nuoffer
- Biocenter, University of Basel, Switzerland
| | | | | | | |
Collapse
|
11
|
Permethylation and tandem mass spectrometry of oligosaccharides having free hexosamine: analysis of the glycoinositol phospholipid anchor glycan from the scrapie prion protein. Anal Biochem 1990; 191:174-82. [PMID: 1981823 DOI: 10.1016/0003-2697(90)90405-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Permethylation of the glycan isolated from the glycoinositol phospholipid (GPI) anchor of the scrapie prion protein (PrPSc) trimethylates a free hexosamine to form a quarternary ammonium salt, substantially increasing the sensitivity for analysis by mass spectrometry. This derivatization induces specific fragmentation reactions in collision-induced dissociation spectra obtained on a four-sector tandem mass spectrometer, identifying the branching pattern of the PrPSc GPI glycan.
Collapse
|
12
|
Lisanti MP, Rodriguez-Boulan E, Saltiel AR. Emerging functional roles for the glycosyl-phosphatidylinositol membrane protein anchor. J Membr Biol 1990; 117:1-10. [PMID: 2144878 DOI: 10.1007/bf01871561] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M P Lisanti
- Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York
| | | | | |
Collapse
|
13
|
Glycolipid precursors for the membrane anchor of Trypanosoma brucei variant surface glycoproteins. I. Can structure of the phosphatidylinositol-specific phospholipase C sensitive and resistant glycolipids. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39306-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
14
|
Roditi I, Pearson TW. The procyclin coat of African trypanosomes (or the not-so-naked trypanosome). ACTA ACUST UNITED AC 1990; 6:79-82. [PMID: 15463304 DOI: 10.1016/0169-4758(90)90216-q] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- I Roditi
- Kernforschungzentrum Karlsruhe, Institut für Genetik und Toxikologie, Karlsruhe, FRG
| | | |
Collapse
|
15
|
Murakata C, Ogawa T. Synthetic study on glycophosphatidyl inositol (GPI) anchor of trypanosoma brucei: Glycoheptaosyl core. Tetrahedron Lett 1990. [DOI: 10.1016/s0040-4039(00)97383-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
16
|
Müller G, Bandlow W. An amphitropic cAMP-binding protein in yeast mitochondria. 2. Phospholipid nature of the membrane anchor. Biochemistry 1989; 28:9968-73. [PMID: 2695165 DOI: 10.1021/bi00452a014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We describe the first example of a mitochondrial protein with a covalently attached phosphatidylinositol moiety acting as a membrane anchor. The protein can be metabolically labeled with both stearic acid and inositol. The stearic acid label is removed by phospholipase D whereupon the protein with the retained inositol label is released from the membrane. This protein is a cAMP receptor of the yeast Saccharomyces cerevisiae and tightly associated with the inner mitochondrial membrane. However, it is converted into a soluble form during incubation of isolated mitochondria with Ca2+ and phospholipid (or lipid derivatives). This transition requires the action of a proteinaceous, N-ethylmaleimide-sensitive component of the intermembrane space and is accompanied by a decrease in the lipophilicity of the cAMP receptor. We propose that the component of the intermembrane space triggers the amphitropic behavior of the mitochondrial lipid-modified cAMP-binding protein through a phospholipase activity.
Collapse
Affiliation(s)
- G Müller
- Institut für Pathologie und Rechtsmedizin Universität Ulm, München, Federal Republic of Germany
| | | |
Collapse
|
17
|
Krakow JL, Doering TL, Masterson WJ, Hart GW, Englund PT. A glycolipid from Trypanosoma brucei related to the variant surface glycoprotein membrane anchor. Mol Biochem Parasitol 1989; 36:263-70. [PMID: 2797062 DOI: 10.1016/0166-6851(89)90174-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The variant surface glycoprotein (VSG) of Trypanosoma brucei is covalently linked to a phosphatidylinositol-containing glycolipid which serves as a membrane anchor. We previously identified a molecule, glycolipid A, which appears to be a biosynthetic precursor to the anchor [9]. In this paper we describe a related molecule, glycolipid C, which is similar to glycolipid A but which is more hydrophobic. Chromatographic analyses indicate that the polar head groups in glycolipids A and C are similar or identical. Both glycolipids contain phosphatidylinositol, but the inositol in glycolipid C is modified by a hydrophobic moiety. Since treatment of glycolipid C with mild alkali results in partial conversion to a molecule chromatographically identical to glycolipid A, it is likely that glycolipid C has an alkali-sensitive hydrophobic group, such as a fatty acid, linked to its inositol moiety.
Collapse
Affiliation(s)
- J L Krakow
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD
| | | | | | | | | |
Collapse
|
18
|
Rosen G, Påhlsson P, Londner MV, Westerman ME, Nilsson B. Structural Analysis of Glycosyl-phosphatidylinositol Antigens of Leishmania major. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81643-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
19
|
Roditi I, Schwarz H, Pearson TW, Beecroft RP, Liu MK, Richardson JP, Bühring HJ, Pleiss J, Bülow R, Williams RO. Procyclin gene expression and loss of the variant surface glycoprotein during differentiation of Trypanosoma brucei. J Cell Biol 1989; 108:737-46. [PMID: 2645304 PMCID: PMC2115453 DOI: 10.1083/jcb.108.2.737] [Citation(s) in RCA: 246] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In the mammalian host, the unicellular flagellate Trypanosoma brucei is covered by a dense surface coat that consists of a single species of macromolecule, the membrane form of the variant surface glycoprotein (mfVSG). After uptake by the insect vector, the tsetse fly, bloodstream-form trypanosomes differentiate to procyclic forms in the fly midgut. Differentiation is characterized by the loss of the mfVSG coat and the acquisition of a new surface glycoprotein, procyclin. In this study, the change in surface glycoprotein composition during differentiation was investigated in vitro. After triggering differentiation, a rapid increase in procyclin-specific mRNA was observed. In contrast, there was a lag of several hours before procyclin could be detected. Procyclin was incorporated and uniformly distributed in the surface coat. The VSG coat was subsequently shed. For a single cell, it took 12-16 h to express a maximum level of procyclin at the surface while the loss of the VSG coat required approximately 4 h. The data are discussed in terms of the possible molecular arrangement of mfVSG and procyclin at the cell surface. Molecular modeling data suggest that a (Asp-Pro)2 (Glu-Pro)22-29 repeat in procyclin assumes a cylindrical shape 14-18 nm in length and 0.9 nm in diameter. This extended shape would enable procyclin to interdigitate between the mfVSG molecules during differentiation, exposing epitopes beyond the 12-15-nm-thick VSG coat.
Collapse
Affiliation(s)
- I Roditi
- Max-Planck-Institut für Biologie, Tübingen, Federal Republic of Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Niemann H, Mayer T, Tamura T. Signals for membrane-associated transport in eukaryotic cells. Subcell Biochem 1989; 15:307-65. [PMID: 2678617 DOI: 10.1007/978-1-4899-1675-4_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
21
|
Hublart M, Mendonça-Previato L, Boutignon F, Huet-Duvillier G, Degand P. Evidence of myristylated disulfide-linked dimer of variant surface glycoprotein of Trypanosoma brucei-brucei. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1989; 92:705-10. [PMID: 2721157 DOI: 10.1016/0305-0491(89)90253-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. Variant surface glycoprotein (VSGs) of Trypanosoma brucei-brucei may exist as a disulfide-linked dimer in both forms: myristylated (mfVSG) and non-myristylated (sVSG), as judge by fluorography and immunoblotting of SDS-PAGE under non-reducing conditions. 2. The dimeric VSG form is labeled with [3H]-myristic acid in our incorporation conditions. 3. AnTat 1.1 trypanosomes preincubated with tunicamycin and incubated with [3H]-myristic acid synthesized a labeled molecule that has an apparent molecular weight slightly smaller than the native form, and that also corresponds to a disulfide-linked dimer.
Collapse
|
22
|
Roberts WL, Santikarn S, Reinhold VN, Rosenberry TL. Structural characterization of the glycoinositol phospholipid membrane anchor of human erythrocyte acetylcholinesterase by fast atom bombardment mass spectrometry. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37350-2] [Citation(s) in RCA: 207] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
23
|
Risse HJ. [African trypanosomes: parasites with protective mechanisms]. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 1988; 75:489-95. [PMID: 3070386 DOI: 10.1007/bf00361282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
African trypanosomes have developed protective mechanisms in order to escape from their hosts' immune attack. New cell surface antigens become sequentially expressed during a chronic infection providing the parasites continuously with immunologically altered faces. The trypanosomal genome contains a considerable repertoire of different genes coding for the surface antigens; they become separately activated and expressed by a variety of novel molecular processes. In addition, the trypanosomal cell surface participates in the protection of the parasites against non-immune defense mechanisms of the host.
Collapse
Affiliation(s)
- H J Risse
- Institut für Veterinärbiochemie der Freien Universität, Berlin
| |
Collapse
|
24
|
Ferguson MA, Homans SW, Dwek RA, Rademacher TW. Glycosyl-phosphatidylinositol moiety that anchors Trypanosoma brucei variant surface glycoprotein to the membrane. Science 1988; 239:753-9. [PMID: 3340856 DOI: 10.1126/science.3340856] [Citation(s) in RCA: 574] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two forms of protein-membrane anchor have been described for the externally disposed glycoproteins of eukaryotic plasma membranes; namely, the hydrophobic transmembrane polypeptide and the complex glycosylphosphatidylinositol (G-PI) moiety. The chemical structures of the major species of G-PI anchors found on a single variant surface glycoprotein (VSG) of the parasitic protozoan Trypanosoma brucei were determined by a combination of nuclear magnetic resonance spectroscopy, mass spectrometry, chemical modification, and exoglycosidase digestions. The G-PI anchor was found to be heterogeneous with respect to monosaccharide sequence, and several novel glycosidic linkages were present. The results are pertinent to the mechanism of the biosynthesis of G-PI anchors.
Collapse
Affiliation(s)
- M A Ferguson
- Oxford Oligosaccharide Group, Department of Biochemistry, University of Oxford, England
| | | | | | | |
Collapse
|
25
|
Abstract
Glycosylated forms of phosphatidylinositol, which have only recently been described in eukaryotic organisms, are now known to play important roles in biological membrane function. These molecules can serve as the sole means by which particular cell-surface proteins are anchored to the membrane. Lipids with similar structures may also be involved in signal transduction mechanisms for the hormone insulin. The utilization of this novel class of lipid molecules for these two distinct functions suggests new mechanisms for the regulation of proteins in biological membranes.
Collapse
Affiliation(s)
- M G Low
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | | |
Collapse
|
26
|
de Almeida ML, Turner MJ, Stambuk BB, Schenkman S. Identification of an acid-lipase in human serum which is capable of solubilizing glycophosphatidylinositol-anchored proteins. Biochem Biophys Res Commun 1988; 150:476-82. [PMID: 3337726 DOI: 10.1016/0006-291x(88)90545-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A lipase has been identified in human serum which can convert the membrane form of the variant surface glycoprotein of Trypanosoma brucei to a water soluble form. The conversion can be monitored by loss of [3H] myristic acid incorporated into the diacylglycerol of the glycophosphatidylinositol membrane anchor of the protein, but does not lead to the exposure of the antigenic determinant in the polar head group of the glycolipid. The serum lipase is a glycoprotein, and is optimally active at pH 5.4. Treatment at 62 degrees for one hour does not inactivate the enzyme, which is inhibited by chelating agents.
Collapse
|