Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The membrane-bound N-acetylgalactosaminyltransferase from porcine submaxillary glands which provides A blood group specificity to mucin has been purified 38,000-fold by affinity chromatography on UDP-hesanolamine-agarose in aqueous Triton X-100. Design of a suitable purification procedure was developed by assessing the strength of interaction between enzyme and affinity adsorbent using batch desorption. The pure transferase has an apparent molecular weight of 100,000 as judged by zonal centrifugation and by sodium dodecyl sulfate polyacrylamide gel electrophoresis in the absence of a reducing agent. The reduced and carboxymethylated protein has an apparent molecular weight of 46,000 and 57,000 as judged by sedimentation equilibrium and sodium dodecyl sulfate polyacrylamide gel electrophoresis, respectively, suggesting that the native enzyme contains two subunits. It is a glycoprotein with a specific activity of 30 micronmol/min/mg of enzyme, which is 55,000 times that reported for the same enzyme isolated from human serum.
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PMID:Porcine A blood group-specific N-acetylgalactosaminyltransferase. I. Purification from porcine submaxillary glands. 1 62

The polysaccharide composition of the human gallbladder well was studied in carcinomas and metaplastic changes of various degrees, and the results obtained were compared with those for the normal material previously presented (Terho, T., and Laitio, M. Biochim. Biophys. Acta 338: 135, 1974). Elevated amounts of acid connective tissue polysaccharides (heparitin and dermatan sulfates as well as chondroitin 4- or 6-sulfate, or both, could be observed in carinomas. In histochemical stainings it was found that in carcinomas and in the two specimens classified as group III (containing the most extensive metaplastic changes at disposal), the intracellular mucin was mainly neutral or nonsulfated acidic. The amounts of sulfated mucin were relatively insignificant. This mucin polysaccharide material was isolated and its composition was determined. It was observed to be large polysaccharide material was isolated and its composition was determined. It was observed to be large molecular (approximate molecular sizes 1 to 2 times 10-6), and to be composed of fucose, galactose, glucosamine, and galactosamine as well as small amounts of sialic acid. The basic structure of these polysaccharides is thus similar to that of normal sulfated mucin. The almost total absence of acid groups, however, causes the polysaccharide material in question to stain in a manner identical with neutral mucin when investigated with histochemical methods. The carcinomas also contained some sulfomucin; its proportion, however, was small as compared with the amounts of nonsulfated acid and neutral mucin in biochemical characterization. A small molecular polysaccharide fraction, assumed to originate in membrane-bound glycoproteins, was isolated from the insoluble gallbladder tissue residue. The proportion of this fraction was larger in carcinomas than in normal material. This rise as well as the rise in the quantity of acid connective tissue polysaccharides is presumably due to the large number of cells in the carcinoma tissue as well as to fibrosis.
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PMID:Polysaccharides of metaplastic mucosa and carcinoma of the gallbladder. 4 29

Five cases of the type of mammary carcinoma that has been designated "signet-ring cell carcinoma" are presented. This tumor is characterized by the presence of numerous cells containing intracellular mucin, without large amounts of extracellular mucin as is seen in colloid (gelatinous, mucinous) carcinoma of the breast. Although such cells may be seen in many mammary carcinomas, they are never as frequent as in the variant described. Ultrastructurally, the most characteristic finding is the presence of numerous intracellular lumina containing material which appears to represent the mucin identified with the light microscope. This finding differs from that in colloid carcinoma, in which the scantier intracellular mucin occurs in the form of intracytoplasmic membrane-bound vesicles. The five tumors in the present series were all associated with either in situ lobular carcinoma or a "sinus catarrh"-like pattern of nodal metastases, or both. On the basis of these light and electron microscopic data, the signet-ring cell carcinoma is suggested as a variant of infiltrating lobular carcinoma, clinically and pathologically distinct from colloid carcinoma.
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PMID:Signet-ring cell carcinoma of the breast. The mucinous variant of infiltrating lobular carcinoma? 17 13

An ultrastructural study of the cell surface of lumen-forming tumors was carried out to determine the distribution of two morphologic markers seen in relation to the microvilli. These are membrane-bound glycocalyceal bodies and microvillous filament cores that penetrate the underlying cytoplasm as rootlets. They were found (especially when in combination) to be valuable in identifying tumors of what is referred to as intestinal-type epithelium, and could be seen in cases in which brush borders were absent. They have been demonstrated in intestinal-type carcinomas of the stomach and gallbladder, in adenocarcinomas of the small and large intestines and pancreatic ducts, in mucin-forming bronchiolar carcinomas, and in certain mucinous ovarian and endocervical tumors. Other tumors, whether mucin-producing or not, have been found to consistently lack these structures.
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PMID:Glycocalyceal bodies and microvillous core rootlets: their value in tumor typing. 58 35

The human pyloric glands are simple or branched tubular glands which spiral through the connective tissue of the lamina propria. They are comprised of three cell types: the pyloric gland (mucous) cell, the parietal cell, and endocrine cells. The mucous cell is the most common cell type in the human pyloric glands and is characterized by an abundance of secretory granules. The secretory granules are usually round in shape and vary considerably in diameter. They are membrane-bound and comprise a heterogeneous population. The larger granules contain a light staining amorphous material and often possess an area of increased electron density near the limiting membrane of the granule giving them a mottled appearance. A smaller, more electron-dense secretory granule also is found both in relation to the Golgi complex and cell apex. The morphological observations indicate that the mechanism of mucin production by the mucous cells of the human pyloric glands may be similar to that reported in other mucin-secreting cells.
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PMID:Ultrastructure of the human pyloric glands with emphasis on the mucous cell component. Part I. 89 81

Pig tracheal epithelium, a site of extensive mucin biosynthesis, contained polypeptide N-acetylgalactosaminyltransferase activity directed towards L-threonine residues. The enzyme preparation was broadly similar in properties to preparations from other tissues, e.g. pig and bovine submaxillary glands, bovine colostrum, BW5147 mouse lymphoma and baby-hamster kidney cells. Enzyme was membrane-bound and was released from microsomal preparations by extraction with Triton X-100. Extracted enzyme had a pH optimum of 7.5, had a requirement for Mn2+ (10 mM) and was inhibited by Na2EDTA. The Km for UDP-N-acetylgalactosamine was 110 microM and that for an octapeptide acceptor (VTPRTPPP) was 3.0 mM at 37 degrees C. Using a range of synthetic peptides of known structure related to TPPP it was established that L-threonine residues were specifically O-glycosylated probably in the alpha-configuration. Synthetic peptides containing the TPPP sequence required a peptide length of five or more for significant acceptor activity. In VTPRTPPP the two threonine residues were similarly glycosylated, as revealed by tryptic cleavage of the glycosylated product and separation of the 3H-labelled fragments. The enzyme preparation also specifically catalysed the transfer of N-acetylgalactosaminyl residues from UDP-N-acetyl[1-3H]galactosamine to bovine submaxillary mucin core protein and to myelin basic protein.
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PMID:Polypeptide N-acetylgalactosaminyltransferase activity in tracheal epithelial microsomes. 137 3

A membrane-bound sialidase (EC 3.2.1.18) was found in procyclic trypomastigotes of Trypanosoma brucei. The mammalian stage bloodstream form, however, displayed no sialidase activity. This sialidase is an integral surface protein, linked to the membrane via a glycosylphosphatidylinositol anchor. After osmotic lysis and solubilization with Triton CF-54, the enzyme was purified 1900-fold by gel filtration and ion exchange chromatography. Its size, as determined by conventional and high-performance liquid gel chromatography, is 67 kDa. The sialidase is active over a broad pH and temperature range with optima at pH 6.9 and 35 degrees C, respectively. No loss of activity is observed after 4 freeze-thaw cycles. T. brucei sialidase activity is inhibited by N-(4-nitrophenyl)oxamic acid and 2-deoxy-2,3-didehydro-N-acetylneuraminic acid, the latter, however, being less effective. N-Acetylneuraminic acid shows no inhibitory effect, whereas a variety of metal ions are potent inhibitors. The sialidase is activated by di- and tricarboxylic acids, but inhibited by chloride. Relative hydrolysis rates of various sialic acid-containing compounds reveal that de-O-acetylated bovine submandibular gland mucin is the preferred substrate and that alpha(2-3)-linkages are hydrolyzed faster than alpha(2-6)-linkages.
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PMID:Purification and characterization of a novel sialidase found in procyclic culture forms of Trypanosoma brucei. 151 30

Mucins are large molecular weight glycoproteins characterized by carbohydrate sugars attached via 'O-glycosidic' linkages to serine or threonine. Mucins are synthesized by a variety of epithelial tissues as membrane-bound or secreted proteins, encoded by several distinct mucin genes. Numerous alterations of mucin-associated carbohydrates can be detected in neoplastic epithelial tissues and on circulating mucins in patients with adenocarcinomas. The expression of various sialyosylated-carbohydrate epitopes may correlate with poor prognosis and enhanced metastatic disease in colorectal adenocarcinomas. Mucin-associated carbohydrate and peptide antigens are currently being investigated for their role in cancer diagnosis, monitoring for progression or metastases, immunotherapy and immunosuppression.
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PMID:Carbohydrate antigens on cancer-associated mucin-like molecules. 172 30

The ultrastructural patterns of neuroendocrine (NE) differentiated breast carcinomas are analyzed and discussed. Reports in the literature describe wide variations in the size of observed dense-core membrane-bound granules and discrepancies in their interpretation. In the present study 24 cases of breast carcinoma with recognized morphologic, histochemical, and immunocytochemical features of NE tumors were investigated. Five different types of dense-core granules of neurosecretory (NS) type (confirmed by the ultrastructural localization of chromogranin A) and five different cell types were recognized. Some amphicrine cells were found to contain both mucin and NS granules. Another notable ultrastructural feature of breast NE carcinomas was the presence of clear vesicles of presynaptic type, which correlated with expression of synaptophysin.
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PMID:Ultrastructural features of neuroendocrine differentiated carcinomas of the breast. 220 Jan 85

Adenocarcinoma of the rete testis is a rare tumor. We describe the ultrastructural appearance of a retroperitoneal adenocarcinoma metastatic from the rete testis, and compare this appearance with that of normal human rete testis. Both normal rete epithelium and the tumor showed deep, narrow nuclear invaginations with apparent nuclear lobulation; small, pleomorphic, electron-dense, membrane-bound granules in the basal cytoplasm; lipid droplets in the apical cytoplasm; and distinctive bulbous cytoplasmic projections along the apical surfaces of the cells. In addition, more general features of glandular tissue were seen. Features notable for their absence were mucin granules, microvilli containing filamentous cores, glycocalyx, and glycocalyceal bodies. The ultrastructural appearance was sufficiently distinctive to suggest that, in the proper clinical context, electron microscopy may serve to support a diagnosis of adenocarcinoma of the rete testis.
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PMID:Ultrastructure of metastatic rete testis adenocarcinoma. 229 71


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