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Nölte I, Jeckel D, Wieland FT, Sohn K. Localization and topology of ratp28, a member of a novel family of putative steroid-binding proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1543:123-30. [PMID: 11087948 DOI: 10.1016/s0167-4838(00)00188-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We have cloned ratp28, a membrane protein from rat liver homologous to the previously described hpr6.6, a putative steroid-binding protein in humans. Ratp28 has a type II topology as determined by protease digestion experiments on intact and detergent-solubilized membranes. Subcellular fractionation by sucrose density centrifugation revealed a distribution for ratp28 identical to Bip as a marker for membranes of the endoplasmic reticulum. In these experiments no association was found with markers for Golgi or plasma membranes, indicating that ratp28 is localized to the endoplasmic reticulum.
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Affiliation(s)
- I Nölte
- Biochemie-Zentrum, Heidelberg (BZH), University of Heidelberg, Im Neuenheimer Feld, 328, D-69120, Heidelberg, Germany
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Schmauser B, Kilian C, Reutter W, Tauber R. Sialoforms of dipeptidylpeptidase IV from rat kidney and liver. Glycobiology 1999; 9:1295-305. [PMID: 10561454 DOI: 10.1093/glycob/9.12.1295] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dipeptidylpeptidase IV (DPP IV, CD26), a serine-type exo- and endopeptidase found in the cell surface membrane of many tissues, was employed as a model membrane glycoprotein to study the expression of sialoforms on cell surface glycoproteins. Native, enzymatically active DPP IV was purified from plasma membranes of kidney and liver by lectin affinity chromatography in conjunction with crown ether anion exchange chromatography. The enzyme was gradient-eluted in continuous fractions, all showing a single polypeptide band of about 100 kDa when separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing, denaturing conditions. Analysis of the purified DPP IV by isoelectric focusing (IEF) showed that it consists of several polypeptides of different isoelectric points (IP) ranging from 5.5 to 7.0. In vitro- desialylation of the enzyme and subsequent isoelectric focusing revealed that the differences in isoelectric points were due to differences in the degree of sialylation. Differences in the degree of sialylation between the fractions were also demonstrated by SDS-PAGE under nonreducing and nondenaturing conditions. Increased sialylation of the enzyme as demonstrated by isoelectric focusing resulted in increased migration velocity in nonreducing and nondenaturing SDS-polyacrylamide gels. In vitro -desialylation of the enzyme and its resialylation confirmed that sialylation was responsible for this extraordinary migration behavior. The native enzyme was predominantly sialylated via alpha 2, 6-linkage, as shown by lectin affinity blotting employing Sambucus nigra agglutinin (SNA) and Maackia amurensis agglutinin (MAA). These findings demonstrate that a distinct membrane glycoprotein may exist in various sialoforms, distinguished from each other by a different number of sialic acid residues. Moreover, these sialoforms can be individually purified by crown ether anion exchange chromatography.
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Affiliation(s)
- B Schmauser
- Institut für Molekularbiologie und Biochemie der Freien Universität Berlin, Arnimallee 22, D-14195 Berlin-Dahlem, Germany
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Stehling P, Grams S, Nuck R, Grunow D, Reutter W, Gohlke M. In vivo modulation of the acidic N-glycans from rat liver dipeptidyl peptidase IV by N-propanoyl-D-mannosamine. Biochem Biophys Res Commun 1999; 263:76-80. [PMID: 10486256 DOI: 10.1006/bbrc.1999.1326] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Derivatives of N-acyl-D-mannosamine differing in the N-acyl-side chain can be metabolically converted into neuraminic acids with corresponding N-acyl side chains. In the present study we show the in vivo modulation of sialic acids in membrane-bound dipeptidyl peptidase IV (CD 26) from rat liver after administration of N-propanoyl-D-mannosamine. Treatment of rats with this unphysiological precursor resulted in an incorporation of N-propanoylneuraminic acid into N-linked glycans of dipeptidyl peptidase IV.
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Affiliation(s)
- P Stehling
- Institut für Molekularbiologie and Biochemie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Arnimallee 22, Berlin-Dahlem, D-14195, Germany
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Bermpohl F, Löster K, Reutter W, Baum O. Rat dipeptidyl peptidase IV (DPP IV) exhibits endopeptidase activity with specificity for denatured fibrillar collagens. FEBS Lett 1998; 428:152-6. [PMID: 9654125 DOI: 10.1016/s0014-5793(98)00515-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Dipeptidyl peptidase IV (DPP IV, CD 26) is an integral membrane serine protease exhibiting a well characterized exopeptidase activity. The present study shows that DPP IV also possesses a novel gelatinase activity and therefore endopeptidase activity, which was directly demonstrated by gelatin zymography. Protease inhibitor profile analysis showed that the endo- and exopeptidase activities of DPP IV share a common active site. Substrate specificity was detected for denatured collagen types I, II, III and V suggesting that DPP IV might contribute to collagen trimming and metabolism. On the basis of these data we propose that DPP IV and the recently sequenced gelatinolytic seprase (FAPalpha) represent a new subfamily of gelatinolytic integral membrane serine proteases.
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Affiliation(s)
- F Bermpohl
- Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Berlin-Dahlem, Germany
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Lannert H, Gorgas K, Meissner I, Wieland FT, Jeckel D. Functional organization of the Golgi apparatus in glycosphingolipid biosynthesis. Lactosylceramide and subsequent glycosphingolipids are formed in the lumen of the late Golgi. J Biol Chem 1998; 273:2939-46. [PMID: 9446606 DOI: 10.1074/jbc.273.5.2939] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Biosynthesis of plasma membrane sphingolipids involves the coordinate action of enzymes localized to individual compartments of the biosynthetic secretory pathway of proteins. These stations include the endoplasmic reticulum and the Golgi apparatus. Although a precise localization of all the enzymes that synthesize glycosphingolipids has not been achieved to date, it is assumed that the sequence of events in glycosphingolipid biosynthesis resembles that in glycoprotein biosynthesis, i.e. that early reactions occur in early stations (endoplasmic reticulum and cis/medial Golgi) of the pathway, and late reactions occur in late stations (trans Golgi/trans Golgi network). Using truncated analogues of ceramide and glucosylceramide that allow measurement of enzyme activities in intact membrane fractions, we have reinvestigated the localization of individual enzymes involved in glycosphingolipid biosynthesis and for the first time studied the localization of lactosylceramide synthase after partial separation of Golgi membranes as previously described (Trinchera, M., and Ghidoni, R. (1989) J. Biol. Chem. 264, 15766-15769). Here, we show that the reactions involved in higher glycosphingolipid biosynthesis, including lactosylceramide synthesis, all reside in the lumen of the late Golgi compartments from rat liver.
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Affiliation(s)
- H Lannert
- Biochemie Zentrum Heidelberg, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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Fan H, Meng W, Kilian C, Grams S, Reutter W. Domain-specific N-glycosylation of the membrane glycoprotein dipeptidylpeptidase IV (CD26) influences its subcellular trafficking, biological stability, enzyme activity and protein folding. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 246:243-51. [PMID: 9210490 DOI: 10.1111/j.1432-1033.1997.00243.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dipeptidyl peptidase IV (DPPIV, CD26) is an N-glycosylated type II plasma membrane protein. The primary structure of rat wild-type DPPIV contains eight potential N-glycosylation sites. To investigate the role of N-glycosylation in the function of DPPIV, three of its asparagine residues were separately converted to glutamine by site-directed mutagenesis. The resulting N-glycosylation mutants of rat DPPIV were studied in stable transfected Chinese hamster ovary cells. All three N-glycosylation mutants of DPPIV showed a reduced half-life, as well as differing degrees of inhibition of the processing of their N-glycans. Mutation of the first (Asn83-->Gln) or eighth (Asn686-->Gln) N-glycosylation site had only a small effect on its enzymatic activity, cell-surface expression and dimer formation, whereas the mutation of the sixth N-glycosylation site (Asn319-->Gln) abolished the enzymatic activity, eliminated cell-surface expression and prevented the dimerization of the DPPIV protein. The mutant [Gln319]DPPIV is retained in the cytoplasm and its degradation was drastically increased. Our data suggest that the N-glycosylation at Asn319 is involved in protein trafficking and correct protein folding.
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Affiliation(s)
- H Fan
- Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Germany.
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Löster K, Baum O, Hofmann W, Reutter W. Chemical cross-linking leads to two high molecular mass aggregates of rat alpha 1 beta 1 integrin differing in their conformation but not in their composition. FEBS Lett 1995; 373:234-8. [PMID: 7589473 DOI: 10.1016/0014-5793(95)01053-h] [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: 01/26/2023]
Abstract
In order to detect protein interactions of the collagen/laminin receptor alpha 1 beta 1 integrin, covalent chemical cross-linking was performed with the homo-bifunctional, amine reactive reagents DSS (disuccinimidylsuberate) and DSP (dithiobis(succinimidylpropionate)). After cross-linking of the 190 kDa rat alpha 1 integrin subunit, immunoblotting revealed two additional, immunoreactive, high molecular mass complexes (M(r) 240/290 k). Generation of the 240/290 kDa aggregates depended on the presence of the intact tertiary protein structure. As shown with immunoaffinity purified proteins, the 240/290 kDa aggregates consist exclusively of alpha 1 and beta 1 integrin subunits. No other cross-linked proteins associated with the alpha 1 or beta 1 subunit were detected. In contrast to the non-cross-linkable alpha 1 beta 1 integrin, the 240/290 kDa aggregates presumably represent active forms of the adhesion receptor, because both bound in vitro to collagen I and IV. This ability of alpha 1 beta 1 integrin to cross-link and produce two additional high molecular mass forms is shared by rat alpha 9 beta 1 integrin. Thus, the cross-linking approach directly indicates that beta 1 integrins occur in different conformations caused by variations in the folding and/or spatial arrangement of their subunits.
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Affiliation(s)
- K Löster
- Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Germany
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Löster K, Baum O, Hofmann W, Reutter W. Characterization of molecular aggregates of alpha 1 beta 1-integrin and other rat liver membrane proteins by combination of size-exclusion chromatography and chemical cross-linking. J Chromatogr A 1995; 711:187-99. [PMID: 7496490 DOI: 10.1016/0021-9673(95)00208-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many membrane proteins display their biological activity in molecular aggregates of interacting counterparts. The analysis of these aggregates remains difficult; especially intermolecular complexes of membrane proteins tend to dissociate or artificially aggregate during detergent extraction out of membranes. Thus, the existence of protein aggregates was investigated by two approaches. First, after modest detergent extraction, the presence of three well characterized rat liver membrane proteins, alpha 1 beta 1-integrin, dipeptidyl aminopeptidase IV (DPP IV) and cell-CAM 105 (CAM = cell adhesion molecule), in aggregates could be demonstrated when investigated by size-exclusion chromatography (SEC) under non-denaturating conditions. However, the applied detergents partially influenced the resolution of the separation reducing the ability to discriminate between native and artificial protein aggregates. To circumvent these problems, a second approach based on covalent cross-linking of native protein complexes by dithiobis(succinimidylpropionate) was combined with the performance of denaturating SEC. Under such optimized some high-molecular-mass complexes of all model proteins consisting of unknown components could also be detected. Taken together, non-denaturating SEC and chemical cross-linking in combination with denaturating SEC represent methodological approaches for the characterization of protein aggregates.
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Affiliation(s)
- K Löster
- Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Dahlem, Germany
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Moehrle MC, Schlagenhauff BE, Klessen C, Rassner G. Aminopeptidase M and dipeptidyl peptidase IV activity in epithelial skin tumors: a histochemical study. J Cutan Pathol 1995; 22:241-7. [PMID: 7593818 DOI: 10.1111/j.1600-0560.1995.tb00745.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The activities of microsomal alanylaminopeptidase (APM EC 3.4.11.2) and of dipeptidyl dipeptidase IV (DPP IV EC 3.4.14.5) were histochemically studied in frozen sections of normal skin, seborrheic keratosis, basal cell carcinoma, solar keratosis, Bowen's disease and squamous cell carcinoma using amino acid- or peptide-4-methoxy-2-naphthylamides as specific chromogenic substrates. Compared to biochemical and immunohistochemical methods, the histochemical technique used in this study allows distinct localization of protease activity within the tumor tissue and the tumor-associated stroma. Strong APM activity was detectable only in the stroma of basal cell carcinoma, a result which reflects the particular tumor-stroma interaction of this semimalignant tumor. APM activity was not detectable in either healthy epidermis or the tumor parenchyma. Altered activity of DPP IV was found in the tumor cells as well as in the surrounding connective tissue: precancerous dermatoses and basal cell carcinomas had higher levels of DPP IV-activity than normal skin or benign seborrheic keratosis. Poorly differentiated malignant squamous cell carcinomas, however, showed no histochemically detectable DPP IV-activity at all. This result is in line with reports of decreased activity of this enzyme in cases of malignancy.
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Affiliation(s)
- M C Moehrle
- Department of Dermatology, University of Tuebingen, Germany
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Abstract
CD26 is a proteolytic enzyme (dipeptidylpeptidase IV) with a wide tissue distribution and a unique specificity. Recent developments indicate that CD26 is a multifunctional molecule that may have important functions in the immune system. Here, Bernhard Fleischer reviews the current knowledge of CD26 and discusses the possible functions of this molecule in T lymphocytes.
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Affiliation(s)
- B Fleischer
- Dept of Medical Microbiology and Immunology, Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany
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Loch N, Tauber R, Becker A, Hartel-Schenk S, Reutter W. Biosynthesis and metabolism of dipeptidylpeptidase IV in primary cultured rat hepatocytes and Morris hepatoma 7777 cells. ACTA ACUST UNITED AC 1992; 210:161-8. [PMID: 1359965 DOI: 10.1111/j.1432-1033.1992.tb17404.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-Glycosylation, biosynthesis and degradation of dipeptidylpeptidase IV (EC 3.4.14.5) (DPP IV) were comparatively studied in primary cultured rat hepatocytes and Morris hepatoma 7777 cells (MH 7777 cells). DPP IV had a molecular mass of 105 kDa in rat hepatocytes and of 103 kDa in MH 7777 cells as assessed by SDS/PAGE under reducing conditions. This difference in molecular mass was caused by differences in covalently attached N-glycans. DPP IV from hepatoma cells contained a higher proportion of N-glycans of the oligomannosidic or hybrid type and therefore migrated at a slightly lower molecular mass. In both cell types DPP IV was initially synthesized as a 97-kDa precursor which was completely susceptible to digestion with endo-beta-N-acetylglucosaminidase H converting the molecular mass to 84 kDa. The precursor was processed to the mature forms of DPP IV, glycosylated with N-glycans mainly of the complex type with a half-life of 20-25 min. The transit of newly synthesized DPP IV to the cell surface displayed identical or very similar kinetics in both cell types with the major portion of DPP IV appearing at the cell surface after 60 min. DPP IV molecules were very slowly degraded in hepatocytes as well as in hepatoma cells with half-lives of approximately 45 h. Inhibition of oligosaccharide processing with 1-deoxymannojirimycin led to the formation of DPP IV molecules containing N-glycans of the oligomannosidic type. This glycosylation variant was degraded with the same half-life as complex-type glycosylated DPP IV. By contrast, inhibition of N-glycosylation with tunicamycin resulted into rapid degradation of non-N-glycosylated DPP IV molecules in both cell types. Non-N-glycosylated DPP IV could not be detected at the cell surface indicating an intracellular proteolytic process soon after biosynthesis.
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Affiliation(s)
- N Loch
- Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Federal Republic of Germany
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Hocher B, Rubens C, Hensen J, Gross P, Bauer C. Intracellular distribution of endothelin-1 receptors in rat liver cells. Biochem Biophys Res Commun 1992; 184:498-503. [PMID: 1314598 DOI: 10.1016/0006-291x(92)91222-c] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We studied the binding of (125I)-endothelin-1 as well as that of the vasopressin analogue (125I)-[8-phenylpropionyl]-LVP to purified plasma membranes, Golgi cisternae and cell nuclei from rat liver. Cell organelles were isolated by differential centrifugation and discontinuous sucrose gradients. Endothelin-1 exhibited specific binding to plasma membranes, Golgi cisternae and nuclei, while the binding of (125I)-[8-phenylpropionyl]-LVP was restricted to the plasma membranes. The number of receptors (Bmax) and the binding constants (Kd) were determined by Scatchard analysis of competition binding studies. In all cases only one class of Et-1 binding sites could be detected. The presence of Et-1 receptors on the Golgi complex either indicates that the receptor is glycosylated within the cisternae or alternatively, there exists a recycling pathway. The unexpected finding of Et-1 receptors on highly purified nuclei suggests that this peptide may exert part of its biological functions intracellularly via the nucleus.
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Affiliation(s)
- B Hocher
- Abteilung für Innere Medizin, Klinikum Steglitz, Freie Universität Berlin, Germany
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