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)

Antibodies raised against purified components of glucose-6-phosphatase were used to study the transmembrane orientation of the complex. Measurements of glucose-6-phosphatase activities and immunoblot analysis of sealed microsomes and detergent-solubilized microsomes after treatment with proteases suggested that most of the catalytic subunit resides within the lumen of the endoplasmic reticulum. In contrast, other components of glucose-6-phosphatase are accessible to the cytoplasm. Treatment of the partially purified glucose-6-phosphatase enzyme with glycopeptide N-glycosidase indicated that the catalytic subunit of the enzyme was a glycoprotein.
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PMID:Transverse topology of glucose-6-phosphatase in rat hepatic endoplasmic reticulum. 185 Feb 36

1. N-glycanase, but not O-glycanase, released carbohydrates from butyrophilin of rat and cow milk lipid globule membranes. 2. 1-Deoxynojirimycin, and inhibitor of glucosidases I and II of the glycoprotein processing pathway, increased the amount or extent of glycosylation of butyrophilin in rat milk lipid globules. 3. Butyrophilin and xanthine oxidase of milk lipid globule membrane had a nearest neighbor relationship, as demonstrated through specific crosslinking of these proteins. 4. From these results it is suggested that butyrophilin has asparagine-linked oligosaccharides which bypass the processing apparatus of endoplasmic reticulum and Golgi apparatus. Butyrophilin may be responsible for anchoring xanthine oxidase to the inner (cytoplasmic) face of milk lipid globule membrane.
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PMID:Butyrophilin of milk lipid globule membrane contains N-linked carbohydrates and cross-links with xanthine oxidase. 252 60

The amino acid sequence of rat brain prostaglandin D synthetase (Urade, Y., Fujimoto, N., and Hayaishi, O. (1985) J. Biol. Chem. 260, 12410-12415) was determined by a combination of cDNA and protein sequencing. cDNA clones specific for this enzyme were isolated from a lambda gt11 rat brain cDNA expression library. Nucleotide sequence analyses of cloned cDNA inserts revealed that this enzyme consisted of a 564- or 549-base pair open reading frame coding for a 188- or 183-amino acid polypeptide with a Mr of 21,232 or 20,749 starting at the first or second ATG. About 60% of the deduced amino acid sequence was confirmed by partial amino acid sequencing of tryptic peptides of the purified enzyme. The recognition sequence for N-glycosylation was seen at two positions of amino acid residues 51-53 (-Asn-Ser-Ser-) and 78-80 (-Asn-Leu-Thr-) counted from the first Met. Both sites were considered to be glycosylated with carbohydrate chains of Mr 3,000, since two smaller proteins with Mr 23,000 and 20,000 were found during deglycosylation of the purified enzyme (Mr 26,000) with N-glycanase. The prostaglandin D synthetase activity was detected in fusion proteins obtained from lysogens with recombinants coding from 34 and 19 nucleotides upstream and 47 and 77 downstream from the first ATG, indicating that the glycosyl chain and about 20 amino acid residues of N terminus were not essential for the enzyme activity. The amino acid composition of the purified enzyme indicated that about 20 residues of hydrophobic amino acids of the N terminus are post-translationally deleted, probably as a signal peptide. These results, together with the immunocytochemical localization of this enzyme to rough-surfaced endoplasmic reticulum and other nuclear membrane of oligodendrocytes (Urade, Y., Fujimoto, N., Kaneko, T., Konishi, A., Mizuno, N., and Hayaishi, O. (1987) J. Biol. Chem. 262, 15132-15136) suggest that this enzyme is a membrane-associated protein.
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PMID:Primary structure of rat brain prostaglandin D synthetase deduced from cDNA sequence. 264 96

Transfer of truncated oligosaccharides to protein in vivo and the structure of Man2GlcNAc2 synthesized by intact yeast (Saccharomyces cerevisiae) were investigated in the alg2 mutant. At the nonpermissive temperature the alg2 mutant accumulates lipid-linked oligosaccharides that migrate on Bio-Gel P4 in the range expected for Man2GlcNAc2 and Man1GlcNAc2 (T.C. Huffaker and P.W. Robbins (1983) Proc. Natl. Acad. Sci. USA 80, 7466-7470). We characterized the oligosaccharides, derived from protein and lipid, by comigration with standards on HPLC and by Smith degradation followed by HPLC. Man2GlcNAc2 and Man1GlcNAc2 are found on protein in alg2, since their release from a protein-containing precipitate of alg2 cells is N-glycanase (peptide-N4[N-acetyl-beta-glucosaminyl]asparagine amidase) dependent. Transfer also occurred in alg2/pAC3 cells, which carry ALG2 on a multicopy plasmid that confers partial correction of the oligosaccharide phenotype. The alg2/pAC3 cells are viable at 36 degrees C. Two isomers of Man2GlcNAc2, Man1----3ManGlcNAc2 and Man1----6ManGlcNAc2, were present on lipid and protein. The transfer of Man2GlcNAc2 and Man1GlcNAc2 to protein by intact cells supports topological models that postulate access by early intermediates to the lumen of the endoplasmic reticulum.
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PMID:Synthesis of lipid-linked oligosaccharides in Saccharomyces cerevisiae: Man2GlcNAc2 and Man1GlcNAc2 are transferred from dolichol to protein in vivo. 266 Jul 43

The biosynthesis and turnover of lipoprotein lipase (LPL) have been investigated in adipose 3T3-F442A cells labeled with [35S]methionine. Pulse-chase experiments, endo-beta-N-acetylglucosaminidase H treatment, and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have indicated that LPL is synthesized in the endoplasmic reticulum as a glycoprotein of Mr = 55,500 bearing two N-oligosaccharide side chains of the high mannose-type. This precursor form of LPL is transported within 10 min to the Golgi apparatus, and this event is accompanied by the formation of a mature species of Mr = 58,000. Treatment of the Mr = 58,000 species with glycopeptidase F yielded a Mr = 51,000 protein similar to that observed after treatment of the Mr = 55,500 precursor form or after inhibition of N-glycosylation in tunicamycin-treated cells. The precursor form of LPL of Mr = 55,500 does not accumulate in the cells since, after a labeling period of 2 h, only the Mr = 58,000 species is detected. It is shown that only 20% of the newly synthesized molecules of Mr = 58,000 are constitutively secreted, whereas 80% are degraded, most likely in lysosomes, as indicated by the inhibitory effect of leupeptin upon the degradation process. Under heparin stimulation, quantitative secretion of the mature form of LPL takes place whereas the intracellular degradation is arrested. Heparin is able to mobilize intracellular LPL without changing the rate of LPL export from the endoplasmic reticulum to the cell surface. Sucrose gradient centrifugation of the material from intracellular cisternae shows that the Mr = 55,500 precursor form is present as a monomer (s = 4.1 S), whereas the Mr = 58,000 mature form is present as a homodimer (s = 6.8 S) to which LPL activity is associated. The results are interpreted as LPL being transiently stored under a dimeric form before its degradation. A sorting process of LPL in the Golgi apparatus, followed by its entry either mainly in a regulated pathway or in a constitutive pathway, is proposed.
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PMID:Biosynthesis of lipoprotein lipase in cultured mouse adipocytes. II. Processing, subunit assembly, and intracellular transport. 275 12

Freshly isolated rat islets and cultured hamster insulinoma cells (HIT T15) were incubated with a membrane-permeable octanoyl tripeptide (N-octanoyl-ASN-TYR-THR-NH2), which contains an acceptor sequence for ASN-linked glycosylation. Labeled octanoyltripeptide (125[I]TYR) was glycosylated by both islets and HIT cells. The carbohydrate moiety of this glycotripeptide was removed by N-glycanase indicating that glycotripeptide was formed in the lumen of endoplasmic reticulum and, subsequently was secreted via the route for secretory protein. Secretion of glycotripeptide began more rapidly than that of insulin newly synthesized from 3[H]leucine. At 30 min glycotripeptide secretion was already significant but, over a 3-h period, it never represented more than 21% of glycotripeptide produced. Glycotripeptide secretion was not affected by compounds shown to regulate insulin secretion (glucose, forskolin, EGTA and streptozotocin). Thus in beta cells, it appears that glycotripeptide secretion is unregulated and that its cellular secretory pathway is different from that for insulin.
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PMID:Unregulated secretion of an exogenous glycotripeptide by rat islets and HIT cells. 284 81

To investigate the possibility that the opioid peptide precursor proenkephalin A was glycosylated, we utilized an antiserum raised against the COOH terminus of Met-enkephalin Arg6-Gly7-Leu8 (MERGL) to identify and characterize enkephalin-containing peptides from extracts of bovine adrenal medulla. Sephadex G-50 gel filtration separated two immunoreactive peaks which had apparent masses of 9 and 6 kDa. Anion-exchange chromatography and reverse-phase high pressure liquid chromatography (HPLC) revealed that the 9-kDa material was a heterogenous mixture of immunoreactive peptides, of which one (9K-MERGL Ia) was purified to homogeneity. The 6-kDa material separated into two major immunoreactive peaks (6K-MERGL I and 6K-MERGL II) on anion-exchange chromatography, and these were obtained in an homogenous form after reverse-phase HPLC. Amino acid sequencing, together with immunological characterization, indicated that the three peptides were identical in chain length, and corresponded to proenkephalin A 116-165. They contained the sequence Asn-Ser-Ser which is a potential N-glycosylation site. In 9K-MERGL Ia, but not the others, automated Edman amino acid sequencing was unable to detect the relevant asparagine residue, suggesting that this residue has been chemically modified. Further investigation of the 9K-MERGL material using lectin affinity chromatography provided direct evidence of glycosylation. Verification of this result was obtained using the specific enzyme glycopeptidase F (glycopeptide-N-glycosidase) which demonstrated that 9K-MERGL contained, in part, N-linked oligosaccharide chains. These results show that an NH2 terminally extended Met-enkephalin Arg6-Gly7-Leu8 variant was N-glycosylated, and hence indicate that the precursor polypeptide proenkephalin A can be glycosylated during translation in the rough endoplasmic reticulum.
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PMID:N-linked glycosylation of a proenkephalin A-derived peptide. Evidence for the glycosylation of an NH2-terminally extended Met-enkephalin Arg6-Gly7-Leu8 variant. 336 71

The biosynthesis and maturation of human sucrase-isomaltase (SI, EC 3.2.1.48-10), was studied in cultured small intestinal biopsy specimens and mucosa explants. Pulse-chase experiments with [35S]methionine revealed one high mannose intermediate of Mr = 210,000 (pro-SIh) which was processed at a slow rate to an endo H-resistant, mature form of Mr = 245,000 (pro-SIc). The fully core-glycosylated form (Mr = 212,000) was detected only when 1-deoxynojirimycin was added to the culture medium, thus indicating that the core sugars undergo rapid processing by rough endoplasmic reticulum membrane-bound glycosidases. The data presented showed that trypsin specifically and instantaneously (within 1 min) cleaves pro-SIc to two subunits Ic (Mr = 145,000) and Sc (Mr = 130,000). Elastase and chymotrypsin are not effective. Enzymic and chemical deglycosylations of SI with endo-beta-N-acetylglucosaminidase F/glycopeptidase F and trifluoromethanesulfonic acid (TFMS) as well as probing for the binding capacity of SI to Helix pomatia lectin demonstrated that pro-SIc, Ic, and Sc are N- and O-glycosylated. Furthermore, the results were indicative of a posttranslational O-glycosylation of pro-SI, since (i) the earliest detectable precursor form, pro-SIh, did not bind to H. pomatia lectin and (ii) its deglycosylation products with both endo-beta-N-acetylglucosamidase H and TFMS were identical. Both the Sc and Ic subunits contain eight N-linked glycan units, at least one of which is of the high mannose type and found on Sc. Finally, Sc, but not Ic, was shown to display at least four populations varying in their content of O-linked glycans. The heterogeneous O-glycosylation pattern of Sc could be correlated with the distal position of this subunit (and its O-glycosylation sites) within the pro-SI molecule, thus affecting the extent of O-linked oligosaccharide processing and their subsequent presentation on the mature molecule.
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PMID:Biosynthesis of the human sucrase-isomaltase complex. Differential O-glycosylation of the sucrase subunit correlates with its position within the enzyme complex. 336 77

Pigmentation-associated antigen (PAA) or gp75 is a glycoprotein localized to the melanosomes of human melanomas and melanocytes to which a mouse monoclonal antibody (AbTA99) has been produced (T. M. Thomson et al. (1985) J. Invest. Dermatol. 85, 169). Treatment of 3H-labeled immunoprecipitated melanoma PAA with alkaline-borohydride, hydrazinolysis, or N-glycanase released three families of carbohydrate chains (I, II, and III). Peak I consists of a major component (Ia) of sialylated triantennary N-linked chains which are partially substituted with fucose on terminal positions as well as on the chitobiose core and a minor component (Ib) which is a sialylated biantennary N-linked species. Peak II was not well characterized but may be a monoantennary complex chain species. Peak III consists of typical N-linked high mannose units with six to seven mannose residues. Melanocyte PAA carbohydrate chains have the same general features as melanoma PAA except that the biantennary complex chain predominates; this difference resembles that observed between the cell surface glycopeptides of transformed animal cells and their nontransformed counterparts. The glycosylation characteristics of this melanosomal glycoprotein are compared with those of glycoproteins from endoplasmic reticulum, Golgi, and lysosomes, and with tyrosinase. It is suggested that the glycosylation pattern is a reflection of the biosynthetic origin and cellular destination of a particular organelle and its constituents.
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PMID:Glycosylation characteristics of pigmentation-associated antigen (GP75): an intracellular glycoprotein of human melanocytes and malignant melanomas. 353 23

Addition of N-acetylgalactosamine to threonine and serine is the first step in the synthesis of O-glycosidically linked oligosaccharides. A UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase (EC 2.4.1.41) from porcine submaxillary glands was recently purified to electrophoretic homogeneity, and polyclonal antibodies against the purified transferase were raised. Immunoblots of porcine, bovine, and ovine submaxillary gland extracts with the anti-transferase antibodies gave a single band and the antibodies reacted equally well with the purified glycosylated and N-glycanase-treated transferase. Immunoelectron microscopic localization of the transferase was achieved in Lowicryl K4M thin sections and frozen-thawed thin sections of porcine and bovine submaxillary gland by using the protein A-gold technique. Specific gold particle labeling was observed in the cis Golgi apparatus and smooth-membraned vesicular structures in close topological relation with it. Labeling was undetectable in the rough endoplasmic reticulum, its transitional elements, and smooth-membraned structures close to them, the trans Golgi apparatus, mucin droplets, and the plasma membrane. The onset of labeling for peptide-bound GalNAc as detected with Vicia villosa isolectin G4 mirrored the transferase immunolocalization as directly shown by double labeling and extended into the trans Golgi apparatus and mucous droplets. Apomucin immunolabeling was found throughout the endoplasmic reticulum and the intermediate compartment and partially overlapped the region of transferase labeling in the Golgi apparatus as demonstrated by double immunolabeling. Thus, the initial step of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase-mediated O-glycosylation in porcine and bovine submaxillary gland cells occurs in the cis Golgi apparatus. The possible involvement of the intermediate compartment remains to be clarified.
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PMID:Subcellular localization of the UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-mediated O-glycosylation reaction in the submaxillary gland. 809 Jul 48


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