Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Milk fat globule membrane (MFGM) enclosing fat droplets in human milk was found to contain a high molecular weight glycoprotein which did not migrate in 10% acrylamide gel on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This glycoprotein (termed PAS-0) was isolated by Sepharose CL-4B chromatography. Isolated PAS-0 gave one band on SDS-PAGE using 5% acrylamide gel (acrylamide : bisacrylamide = 4 : 1, w/w) and gave one peak on analytical ultracentrifugation, indicating its homogeneity. PAS-0 was rich in serine, threonine, proline, glycine, and alanine. In contrast, contents of sulfur-containing amino acids were very low. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid were detected as constituent sugars of PAS-0 and the total carbohydrate content was about 50%. Alkali-borohydride treatment suggested that the carbohydrate moiety was linked to the polypeptide core with O-glycosidic bond(s). There results suggested that PAS-0 was a mucin-like glycoprotein. PAS-0 was shown to be resistant to pepsin, trypsin and chymotrypsin digestion, but susceptible to Pronase and Subtilisin BPN'. Extraction of intact milk fat globules (cream) with MgCl2 and guanidine hydrochloride solutions suggested that PAS-0 was an intrinsic component of MFGM. Digestion of cream with Subtilisin BPN' demonstrated that PAS-0 was located on the external surface of fat globules and was accessible to molecules outside the globules. By agglutination-inhibition tests using eight lectins, PAS-0 was suggested to act as surface receptors for Ricinus communis agglutinin, wheat germ agglutinin and peanut agglutinin.
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PMID:Isolation and characterization of mucin-like glycoprotein in human milk fat globule membrane. 706 73

A sialomucin from mouse submandibular glands was treated with mild base-Me2SO. This treatment cleaves O-glycosylically linked oligosaccharides, but preserves the integrity of the protein core. After treatment with mild base-Me2SO, 49.2% (by weight) of the oligosaccharides were removed from the polypeptide; they were composed of residues of 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-galactose, sialic acid, and D-galactose. These oligosaccharides were linked O-glycosylically via 2-acetamido-2-deoxy-D-galactose. Chromatography of the base-Me2SO-treated mucin on Sephacryl S-300 indicated that the protein core, with its base-resistant oligosaccharides, is a single, high-molecular-weight species. The mild-base-resistant linkages remaining on the protein core (50.8% of the total carbohydrates by weight) also contained D-mannose. The presence of these mild-base-resistant linkages, and the formation of 2-acetamido-2-deoxy-D-glucitol following treatment with M NaOH-M NaBH4, confirmed the presence of N-glycosylic linkages.
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PMID:A mouse submandibular sialomucin containing both N- and O-glycosylic linkages. 715 Oct 59

Gastric mucin plays an important role in the protection of the stomach wall from chemical, microbiological and mechanical damage. We have previously isolated human gastric mucus glycoproteins and raised a polyclonal antiserum against these macromolecules. This antiserum specifically reacted with gastric mucins in immunoblotting experiments and stained mucous granules at the apical side of gastric surface epithelial cells. A similar staining pattern was obtained after incubation with an antiserum against rat gastric mucin. Next we used the antiserum in pulse-chase experiments of human stomach tissue explants. After short labelling periods with [35S]methionine and [35S]cysteine, the antiserum reacted with a polypeptide with an apparent molecular mass of approx. 500 kDa as determined by SDS/PAGE, which was converted after 90 min into a heterogeneous high-molecular-mass glycoprotein. This high-molecular-mass form, but not the 500 kDa polypeptide, was detectable in the culture medium after 2 h. This strongly suggests that the 500 kDa polypeptide is the precursor of the purified gastric mucin. Analysis of pulse-chase experiments by non-reducing SDS/PAGE revealed that the precursors form disulphide-linked oligomers early in biosynthesis, before the addition of O-linked sugars. After preincubation with the N-glycosylation inhibitor, tunicamycin, the apparent molecular mass of the precursor decreased marginally but consistently, indicating that N-linked glycan chains are present on the mucin precursor.
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PMID:Identification of a human gastric mucin precursor: N-linked glycosylation and oligomerization. 752 92

Mucins are very heavily O-glycosylated glycoproteins. For in depth studies on the cell biological aspects of mucins, anti-polypeptide antibodies are essential. We therefore developed a method for the preparation and screening of polyclonal antisera against mucin peptide epitopes. Mucins from five different tissues were isolated using CsCl/guanidinium.HCl density gradient centrifugation, and polyclonal antisera were prepared. Specificity for mucin peptide epitopes was determined by Western blotting, immunohistochemistry, and immunoprecipitation. The versatility of each anti-mucin antiserum for the study of mucin biosynthesis was tested in metabolic labeling experiments on tissue explants. All polyclonal antisera were directed primarily against peptide epitopes of mucin precursors as well as of fully glycosylated mucins. Each of the polyclonal antisera enabled us to study the mucin biosynthesis in the organ where the mucin was isolated from originally. Our mucin isolation method yields very pure mucins with sufficiently intact polypeptides to reproducibly elicit polyclonal anti-polypeptide antisera. As the sera recognized the polypeptides, primarily independent of the state of O-glycosylation, the intermediate steps in the biosynthesis of the mucins could be identified.
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PMID:Preparation of anti-mucin polypeptide antisera to study mucin biosynthesis. 754 Aug 9

P-selectin glycoprotein ligand 1 (PSGL-1) is a mucin-like glycoprotein expressed on the surface of myeloid cells and serves as the high affinity counterreceptor for P-selectin. The PSGL-1-P-selectin interaction is calcium dependent and requires presentation of sialyl-Lewisx (sLex)-type structures on the O-linked glycans of PSGL-1. We report here the identification of a non-carbohydrate component of the binding determinant that is critical for high affinity binding to P-selectin. Located within the first 19 amino acids, this anionic polypeptide segment contains at least one sulfated tyrosine residue. We propose that this sulfotyrosine-containing segment of PSGL-1, in conjunction with sLex presented on O-linked glycans, constitutes the high affinity P-selectin-binding site.
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PMID:A sulfated peptide segment at the amino terminus of PSGL-1 is critical for P-selectin binding. 758 49

The glycoprotein from cultured cells of D. melanogaster, also detected in various insect tissues as a component of the extracellular matrix, was characterized as a mucin-type glycoprotein not yet described in invertebrates. This glycoprotein with an apparent molecular mass of approximately 90 kDa contains about 40% of carbohydrates, largely represented mainly by GalNAc and Gal; its polypeptide moiety is enriched with Thr, Ser, Pro and Gly. An analysis of oligosaccharides liberated by treatment of the glycoprotein with alkaline NaBH4 or O-glycanase (endo-alpha-N-acetylgalactosaminidase) revealed Gal(beta 1-3)GalNAc as the major type of the sugar chains. About half of the Thr + Ser residues in the glycoprotein were estimated as O-glycosidically linked with the disaccharide units.
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PMID:[Glycoproteins from Drosophila melanogaster cell culture contains O-bound carbohydrate chains of the Gal(beta1-3)GalNAc type]. 766 5

Serum testing for the tumor markers CA 15-3 and mucin-like carcinoma-associated antigen (MCA) was performed in 144 patients with breast cancer. Of those patients, 127 were also tested for a third tumor marker, tissue polypeptide-specific antigen (TPS). At the time of testing, 73 patients (51%) were without evidence of disease and 71 patients (49%) had active disease. Mean follow-up time was 16 months. Positivity rates were: 29.8% for CA 15-3, 47.2% for MCA, and 58.3% for TPS. Mean value for patients with no evidence of disease as compared to patients with active disease was 21 U/ml and 117 U/ml for CA 15-3 (P = 0.001), 10.2 kU/l and 22.6 kU/l for MCA (P = 0.001), and 148 U/l and 310 U/l for TPS (P = 0.02). Two year actuarial survival, according to values below and above an established cutoff for CA 15-3 were 80% and 31% (P < 0.001), 75% and 45% for MCA (P < 0.01), and 82% and 50% for TPS (P < 0.01). We conclude that CA 15-3, MCA and TPS values reflect disease state and prognosis in breast cancer patients.
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PMID:CA 15-3, mucin-like carcinoma-associated antigen and tissue polypeptide-specific antigen: correlation to disease state and prognosis in breast cancer patients. 774 85

Mucin glycoproteins play an important role in the initial stages of gall-stone formation by a currently largely unknown mechanism. Understanding the structure of gall-bladder mucin is necessary to comprehend the mechanism by which cholesterol monohydrate crystals aggregate. Three successive CsCl-gradient-ultracentrifugation steps were used to purify human gall-bladder mucin from gall-bladder tissue. The isolated macromolecules had a typical mucin-like monosaccharide composition and appeared as heterogeneous high-M(r) glycoproteins on SDS/PAGE. A polyclonal antiserum was raised against these molecules and the specificity of the antiserum was ascertained by immunoblotting. The antiserum specifically stained mucous granules at the apical side of all gall-bladder epithelial cells in neck, fundus and body. The antibody was subsequently used to immunoprecipitate the mucin and biosynthetic intermediates from gall-bladder-tissue homogenates. An early biosynthetic precursor of the isolated mucin was identified by SDS/PAGE as a single polypeptide with an apparent M(r) of approx. 470,000. This precursor protein was converted after 1 h into a heterogeneous high-M(r) glycoconjugate with an electrophoretic mobility similar to that of the purified mucin. The mature mucin, but not the precursor, was secreted into the culture medium, starting at 1 h. As shown by SDS/PAGE under non-reducing conditions, the precursors form disulphide-linked oligomers. Using the N-glycosylation inhibitor tunicamycin, the apparent M(r) of the precursor was decreased to approx. 410,000, indicating that N-linked glycan chains are attached to the precursor polypeptide.
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PMID:Biosynthesis of a human gall-bladder mucin. 781 75

In patients with breast cancer no tumor markers giving satisfactory results have been found yet. The aim of our investigation was to compare the usefulness of newly developed tumor markers with the most common used carcinoembryonic antigen and cancer antigen (CA) 15-3. We evaluated the concentrations of carcinoma-associated antigen (CA) 549, carcinoma-associated mucin antigen (CA M) 26 and CA M 29, and the proliferation markers tissue polypeptide antigen (TPA) and tissue polypeptide-specific antigen (TPS) in 84 breast cancer patients with disease progression and in 69 patients with no evidence of disease after surgery for breast cancer. Using receiver-operating characteristic curves (ROC curves) we were able to demonstrate increased sensitivity and specificity of all tested tumor markers in patients with metastatic disease compared with local disease. In our investigation TPA is superior to TPS in all disease states. In local disease, none of the tested markers shows satisfying results. In metastatic disease, the new mucin markers CA M 26 and CA M 29 show slightly better results than CA 15-3 although their ROC curves are nearly congruent. CA 549 is exceeded by the other mucin markers. The best results in this investigation were obtained with CA M 29. The overall results concerning the detection of small tumor masses (i.e. local disease) were unsatisfactory.
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PMID:New mucin-like cancer-associated antigens (CA M 26, CA M 29 and CA 549) and a new proliferation marker (TPS) in patients with primary or advanced breast cancer. 785 74

A mucin-motif peptide in the one-letter code T T T P S P P M T T P I T P P A, representative of the human intestinal mucin tandem repeat sequence (MUC2), containing several threonine residues in clusters, was used as an acceptor substrate to investigate the effect of peptide structure on the activity of crude preparation of human gastric UDP-GalNAc:polypeptide N-acetyl galactosaminyltransferases. High-performance liquid chromatography was performed to separate the different products of the in vitro O-glycosylated reaction. The electrospray mass spectrometry was used to identify the different masses (m/z) of these products. Although the m/z of glycopeptide(s) could be higher than the detection limits of the spectrometer, an accurate study of the doubly charged ions allowed us to demonstrate the linkage of more than two sugars. Hence, the peptide MUC2 will accept at least four carbohydrate residues but the exact substituted positions should be confirmed by further sequence determination.
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PMID:Analysis by electrospray mass spectrometry of glycopeptides from the in vitro O-glycosylation reaction using human mucin motif peptide. 786 66


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