Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.52 (PNGase F)
 1,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dipeptidyl peptidase IV (DPP IV) is a serine exopeptidase expressed at high levels in rat kidney, liver and lung. We established eight monoclonal antibodies against partially purified DPP IV from rat liver plasma membranes. By means of a competitive dot blot assay with purified DPP IV, these antibodies were shown to recognize four different epitopes of the glycoprotein, designated A - D. The epitopes are located on the extracellular domain of DPP IV, as shown by papain digestion of liver plasma membranes. Treatment of DPP IV with neuraminidase and glycopeptide N-glycosidase F, as well as incubation of hepatocytes with the alpha-mannosidase I inhibitor deoxymannojirimycin, revealed that epitope A may be formed by a mannose-rich sugar chain and epitope D might represent a complex carbohydrate structure in the mature glycoprotein, while the epitopes B and C are formed by the protein moiety. Concanavalin A reduced the binding of monoclonal antibody to epitope A by 78%. Binding to epitope D was blocked by 73% with wheat germ lectin, and by more than 99% with sialic acid; epitopes B and C were unaffected by any of the lectins or sugars tested. The immunological cross-reactivity with DPP IV from Morris hepatoma 7777 was demonstrated with monoclonal antibodies against epitopes A-C. Epitope D was not recognized on hepatoma DPP IV. However, in addition to DPP IV, four hepatoma plasma membrane glycoproteins were precipitated by the monoclonal antibody against the epitope D, indicating that this epitope is not uniquely restricted to DPP IV.
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PMID:Development of monoclonal antibodies against different protein and carbohydrate epitopes of dipeptidyl peptidase IV from rat liver plasma membranes. 170 62

We previously described a developmentally regulated, Mr 115,000 (reduced) and 110,000/128,000 (nonreduced) mouse T cell-activating molecule (THAM) also expressed on a variety of epithelial cell surfaces, and associated with neutral exoaminopeptidase activity. In the present study, we show that THAM is the mouse counterpart of the human T cell-activating ectoenzyme CD26 (dipeptidyl peptidase IV, DPP IV) and that highly purified THAM lacks neutral exoaminopeptidase activity. This conclusion is based on the following: 1) the N-terminal segments of the THAM Mr 110,000 and 128,000 components shared the same amino acid sequence with the rat DPP IV. These N-termini comprised a short intracytoplasmic tail of six residues followed by a downstream hydrophobic transmembrane segment. 2) THAM-specific mAb H194-112-Affi-Gel immunoadsorbent was capable of removing DPP IV enzymatic activity from mouse thymoma cell detergent extracts. 3) H194-112 reactivity pattern on developing thymocytes was found to parallel that previously reported for membrane-bound DPP IV enzymatic activity. The extent of THAM N-glycosylation, as measured by N-glycanase treatment of H194-112 immunoprecipitates, was found to be similar to that of human and rat DPP IV (i.e., approximately 20 kDa). Cross-linking experiments indicated that THAM was expressed at the cell surface as a dimer of approximately 220 kDa. Its two subunits were found to be structurally related but not identical as shown by their different Mr under nonreducing conditions and by their slightly distinct peptide profiles after proteolytic cleavage. We conclude from these data that DPP IV, in addition to its extracellular matrix receptor and ectoenzymatic functions, is a T cell-activating structure in both human and mouse species.
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PMID:Evidence that thymocyte-activating molecule is mouse CD26 (dipeptidyl peptidase IV). 171 7

DPL2 (DPP10) found at chromosome 2q14.1 is a member of the dipeptidyl peptidase IV (DPIV) gene family. Here we characterize a novel short DPL2 isoform (DPL2-s), a 789-amino acid protein, that differs from the previously described long DPL2 isoform (DPL2-l) at the N-terminal cytoplasmic domain by 13 amino acids. The two DPL2 isoforms use alternate first exons. DPL2 mRNA was expressed mainly in the brain and pancreas. Multiple forms of recombinant DPL2-s protein were observed in 293T cells, having mobilities 96 kDa, 100 kDa, and approximately 250 kDa which may represent soluble DPL2, transmembrane DPL2 and multimeric DPL2 respectively. DPL2 is glycosylated as a band shift is observed following PNGase F deglycosylation. DPL2-s was expressed primarily on the cell surface of transfected 293T and PC12 cells. DPL2-s exhibits high sequence homology with other DPIV peptidases, but lacks a catalytic serine residue and lacks dipeptidyl peptidase activity. Substitutions of Gly(644)-->Ser, Lys(643)Gly(644)-->TrpSer, or Asp(561)Lys(643)Gly(644)-->TyrTrpSer in the catalytic motif did not confer dipeptidyl peptidase activity upon DPL2-s. Thus, although DPL2 is similar in structure and sequence to the other dipeptidyl peptidases, it lacks vital residues required to confer dipeptidyl peptidase activity and has instead evolved features that enable it to act as an important component of voltage-gated potassium channels.
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PMID:Molecular characterization of a novel dipeptidyl peptidase like 2-short form (DPL2-s) that is highly expressed in the brain and lacks dipeptidyl peptidase activity. 1629 Feb 53

The serum mannan-binding protein (MBP) is a host defense C-type lectin specific for mannose, N-acetylglucosamine, and fucose residues, and exhibits growth inhibitory activity toward human colorectal carcinoma cells. The MBP-ligand oligosaccharides (MLO) isolated from a human colorectal carcinoma cell line, SW1116, are large, multiantennary N-glycans with highly fucosylated polylactosamine-type structures having Le(b)-Le(a) or tandem repeats of the Le(a) structure at their nonreducing ends. In this study, we isolated the major MBP-ligand glycoproteins from SW1116 cell lysates with an MBP column and identified them as CD26/dipeptidyl peptidase IV (DPPIV) (110 kDa) and CD98 heavy chain (CD98hc)/4F2hc (82 kDa). Glycosidase digestion revealed that CD26 contained such complex-type N-glycans that appear to mediate the MBP binding. MALDI-MS of the N-glycans released from CD26 by PNGase F demonstrated conclusively that CD26 is the major MLO-carrying protein. More interestingly, a comparison of the N-glycans released from the MBP-binding and non-MBP-binding glycopeptides suggested that complex-type N-glycans carrying a minimum of 4 Le(a)/Le(b) epitopes arranged either as multimeric tandem repeats or terminal epitopes on multiantennary structures are critically important for the high affinity binding to MBP. Analysis of the N-glycan attachment sites demonstrated that the high affinity MLO was expressed preferentially at some N-glycosylation sites, but this site preference was not so stringent. Finally, hypothetical 3D models of tandem repeats of the Le(a) epitope and the MBP-Lewis oligosaccharide complex were presented.
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PMID:Highly fucosylated N-glycan ligands for mannan-binding protein expressed specifically on CD26 (DPPVI) isolated from a human colorectal carcinoma cell line, SW1116. 1912 45