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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The subcellular distribution of adenyl cyclase was investigated in small intestinal epithelial cells. Enterocytes were isolated, disrupted and the resulting membranes fractionated by differential and sucrose gradient centrifugation. Separation of luminal (brush border) and contra-luminal (basolateral) plasma membrane was achieved on a discontinuous sucrose gradient. The activity of adenyl cyclase was followed during fractionation in relation to other enzymes, notably those considered as markers for luminal and contraluminal plasma membrane. The luminal membrane was identified by the membrane-bound enzymes sucrase and alkaline phosphatase and the basolateral region by (Na+ + K+)-ATPase. Enrichment of the former two enzymes in purified luminal plasma membrane was 8-fold over cells and that of (Na+ + K+)-ATPase in purified bisolateral plasma membranes was 13-fold. F--activated adenyl cyclase co-purified with (Na+ + K+)-ATPase, suggesting a common localization on the plasma membrane. The distribution of K+-stimulated phosphatase and 5'-nucleotidase also followed (Na+ + K+)-ATPase during fractionation.
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PMID:The surface membrane of the small intestinal epithelial cell. I. Localization of adenyl cyclase. 17 91

The possible role of cytoplasmic microtubules in the renal handling of phosphate and its regulation by parathyroid hormone (PTH) was evaluated with colchicine, a microtubule-disrupting agent. Colchicine-treated rats were thyroparathyroidectomized (TPTX) and subsequently infused with PTH. Treatment with a total dose of 1 mg colchicine had no effect on glomerular filtration rate or fractional excretions of sodium and potassium. Fractional excretion of phosphate in colchicine-treated TPTX rats was significantly higher compared with TPTX controls. After PTH infusion, control rats responded with increases in fractional excretion of phosphate and urinary cyclic AMP but colchicine-treated rats had variable and insignificant changes in both parameters. Fractional excretion of sodium and potassium did not change significantly after PTH. Renal cortical activities of cyclic AMP phosphodiesterase, soluble alkaline phosphatase, cytochrome oxidase, leucine aminopeptidase, or basal adenylate cyclase were not significantly affected by colchicine treatment. On the other hand, stimulation of adenylate cyclase by a submaximal dose of PTH was markedly decreased in colchicine-treated rats, and the activity of membrane-bound alkaline phosphatase was also significantly decreased. The binding of radioactive colchicine in renal cortical extracts from rats treated with colchicine was significantly diminished. These results suggest that disruption of cytoplasmic microtubules in renal cortical cells interferes with phosphate transport and its regulation by PTH.
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PMID:Effect of colchicine on urinary phosphate and regulation by parathyroid hormone. 18 12

Solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase. The activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes. Some data were obtained on the localization of alkaline phosphatase in a hydrophobic region, possibly in lipid bilayer and polyphosphatase in the surface layers of the membrane.
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PMID:[Effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in Escherichia coli cells with repressed and depressed biosynthesis of these enzymes]. 18 55

The UHF fraction from NIL 8 hamster embryo fibroblasts contains the LETS protein and several other major proteins. It exhibits three enzymatic activities in significant amounts: 5'-nucleotidase, alkaline phosphatase, and galactosyl transferase. The latter two appear to be different from the membrane-bound enzymes. This fraction is heavily stained with ruthenium red, a dye specific for the cell coat in intact cells. A comparable fraction from hamster sarcoma virus-transformed cells exhibits a similar overall protein composition but lacks at least three major proteins, including the LETS protein. Compared to NIL 8 cells, the distribution of alkaline phosphatase in fractions from these cells is different, and the level of galactosyl transferase in the UHF is much reduced.
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PMID:Cell surface coat of hamster fibroblasts. 29 62

Polysomes containing nascent chains of alkaline phosphatase have been isolated from a membrane-bound polysome preparation. Indirect immunoprecipitation using conformation-specific antibodies has been employed. This technique provides a good enrichment of these polyribosomes since routinely no more than than 10--15% of non-specific immunoprecipitation was observed. The yield of the procedure is generally 40% but can be increased if higher non-specific immunoprecipitation is tolerated. Antibodies, previously described, directed against uncoiled or folded monomers of alkaline phosphatase can be used as primary antibody to recognize the nascent chains contained in membrane-bound polysomes which suggests that these chains are partially folded.
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PMID:Evidence for synthesis of alkaline phosphatase on membrane-bound polysomes in Escherichia coli. 35 May 86

The activity of the membrane-bound enzymes of the microvillous zone of the entreocytes (maltase, sucrase, trehalase, lactase, cellobiase, alkaline phosphatase and leucylaminopeptidase) was studied in mucosal smears from the proximal jejunum, ileum, caecum and sigmoid flexure in a group of control (C) (8) and germ-free (GF) (7) rabbits. The trypsin and chymotrypsin activity of the contents of the ileum, caecum and sigmoid flexure was studied in 6 C, 5 GF and 5 monocontaminated (MC) rabbits. In summing up it can be stated that the individual membrane-bound enzymes have a different gradient in the various intestinal segments of C and GF rabbits and that they differ reciprocally in character. The maximum statistically significant differences between GF and C rabbits were found in the ileum; in the jejunum they were somewhat smaller and in the caecum smaller still (in this localization the difference was C versus GF). Striking differences in the proportion of the individual disaccharidases were found inthe jejunum and ileum of C rabbits compared with GF rabbits, in which, in both these segments of small intestine the relationship maltase greater than sucrase greater than trehalase greater than lactase was preserved. The proteolytic activity of the intestinal contents likewise had a different gradient character in C, MC and GF rabbits. The maximum activities (especially trypsin) were found in MC animals. The microbial flora is one of the factors regulating the enzymatic activities of the microvillous zone of the enterocytes and it also significantly influences the proteolytic activity of the intestinal contents. This influence is particularly marked in the distal part of the alimentary tube.
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PMID:Digestive enzymes of the mucosa of the small intestine and trypsin and chymotrypsin proteolytic activity of the intestinal contents of germ-free, monocontaminated and conventional rabbits. 35 55

The effects of liposomes prepared from the E. coli lipids on the activity of soluble alkaline phosphatase and on the complementation reaction between its subunits were studied. It was shown that the liposomes nonspecifically catalyze the dimerization of the enzyme subunits without changing the dimer activity. The effects of phospholipases A2 and C on the activity of membrane-bound alkaline phosphatase were studied. An interrelationship was found between the level of hydrolysis of membrane phosphatidyl glycerol (PG) by these enzymes and the changes in the activity of membrane-bound alkaline phosphatase. It was also shown that PG is less accessible to the effects of phospholipases in the cells with derepressed biosynthesis of alkaline phosphatase. It is assumed that the membrane PG interacts with the membrane-bound alkaline phosphatase during its translocation into the periplasm.
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PMID:[Phospholipids of E. coli and activity of alkaline phosphatase]. 38 98

1. The proteins of the intestinal microvillus membrane have been studied during post-natal development in the rat (days 12--37). 2. In suckling animals (up to age 20 days), the majority of alkaline phosphatase, glucoamylase and lactase activities in the distal half of the intestine were located in the supernatant fraction (100000 X g, 60 min). These enzymes were attached to the membrane from the proximal intestine at all ages. 3. Alkaline phosphatase, maltase and lactase activities in the supernatant fractions chromatographed in Sephadex G-200 in positions similar to the corresponding membrane enzyme. Corresponding activities for lysosomal counter-parts of maltase and lactase present in the supernatant fraction chromatographed differently. Moreover, pH optimum of the soluble enzymes was 9.2 for phosphatase and 5.5--6.0 for glycoamylase and lactase. The soluble lactase and alkaline phosphatase were inhibited minimally by p-chloromercuribenzoate, and sodium fluoride respectively. L-Phenylalanine (20 mM) did inhibit the soluble phosphatase by 90%. Thus, the soluble enzymes are not mainly of the lysosomal origin, but have characteristics of membrane-bound enzymes. 4. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed 18 protein bands which were present in adult membranes. Two other proteins were unique for membranes of distal intestine in suckling rats. The proteins corresponding to known enzyme activity changed as expected with age (e.g. sucrase, maltase increased, lactase decreased). Most of the other proteins were also altered in amount during development. Thus, the changes in the microvillus membrane during development in the rat are not limited to specific enzymes.
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PMID:Development of intestinal brush border membrane proteins in the rat. 41 9

Verrucose formations were found on the surface of fully developed sporocysts of E. pancreaticum Janson, 1889 at the site where the attenuated proboscis-like anterior portion widens into the posterior portion. Under these verrucose formations is always a group of gland cells. Their narrowed processes pass at a common site through the muscle layer and above this layer again slightly widen and project above the neighbouring tegument. The tegument of the verrucose formation differs from the neighbouring tegument of the sporocyst. In the cytoplasm of the gland cells there are large, spherical membrane-bound bodies containing proteins with tryptophan, tyrosine and SH groups. These bodies do not have any activity of alkaline phosphatase, acid phosphatase or nonspecific esterase. Besides these protein bodies the perinuclear cytoplasm is filled with beta glycogen particles and many cisternae of endoplasmic reticulum. The processes of these cells contain thick fibriles. The verrucose formations with the gland cells seem to serve for attachement and lysis. This function is applied not only during the development of the sporocyst, but also during its release from the site of location and penetration through the snail tissue.
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PMID:Morphology, histochemistry and ultrahistochemistry of special verrucose formations in daughter sporocyst of Eurytrema pancreaticum. 64 May 22

The carotid artery of the rabbit is a suitable blood vessel to study radiation induced atheromatosis in hypercholesteremic animals, because no plaque formation occurs within two months after the start of a 0.5% cholesterol diet. Cholesterol contents as high as 2% however, do give atheromatous plaques in the carotid artery without prior irradiation. As early as five hours after local irradiation of the carotid artery activation of the plasma membrane-bound enzyme alkaline phosphatase could be observed in some intimal cells. Two to three days after irradiation the activity disappeared. This phenomenon was observed in normo-and hypercholesteremic irradiated arteries. Depending on the lipid content of the blood, infiltration of lipids was observed at one day after the irradiation or later, accompanied by activation of beta-glucuronidase in the innermost layer of medial cells. Hereafter plaque formation started and cell proliferation could be found in the subendothelial space. It is assumed that because of the irradiation, the endothelial cells of the carotid artery are damaged in such a way that they do not function properly as a barrier against lipoprotein entrance from the blood into the arterial wall. The lipid infiltration caused lysosomal activation and probably cellular proliferation.
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PMID:Initial events in radiation-induced atheromatosis. II. Damage to intimal cells. 71 13


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