Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Colchicine- and vinblastine-induced depolymerization of microtubules (MTs) in the intestinal epithelium of rats and mice resulted in significant delivery of three apical membrane proteins (alkaline phosphatase, sucrase-isomaltase, and aminopeptidase N) to the basolateral membrane domain. In addition, typical brush borders (BBs) occurred at the basolateral cell surface, consisting of numerous microvilli that contained the four major components of the cytoskeleton of apical microvilli (actin, villin, fimbrin, and the 110-kD protein). Formation of basolateral microvilli required polymerization of actin and proceeded at glycocalyx-studded plaques that resembled the dense plaques located at the tips of apical microvilli. BBs from the basolateral membrane became internalized into BB-containing vacuoles which served as recipient organelles for newly synthesized apical membrane proteins. The BB vacuoles fused with each other and finally were inserted into the apical BB. Polarized distribution of Na+,K+-ATPase, a basolateral membrane protein, was not affected by drug-induced depolymerization of MTs. These observations indicate that Golgi-derived carrier vesicles (CVs) containing apical membrane proteins are vectorially guided to the apical cell surface by a retrograde transport along MTs. MTs are uniformly oriented towards a narrow space underneath the apical terminal web (termed subterminal space) that contains MT-organizing properties and controls polarized alignment of MTs. In contrast to apical CVs, targeting of basolateral CVs appears to be independent of MTs but demands a barrier at the apical membrane domain that prevents basolateral CVs from apical fusion (transport barrier hypothesis).
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PMID:Role of microtubules in polarized delivery of apical membrane proteins to the brush border of the intestinal epithelium. 256 63

A comprehensive survey of 11 peptidases, all of which are markers for renal microvillar membranes, has been made in membrane fractions prepared from pig choroid plexus. Two fractionation schemes were explored, both depending on a MgCl2-precipitation step, the preferred one having advantages in speed and yield of the activities. The specific activities of the peptidases in the choroid-plexus membranes were, with the exception of carboxypeptidase M, lower than in renal microvillar membranes: those of aminopeptidase N, peptidyl dipeptidase A ('angiotensin-converting enzyme') and gamma-glutamyltransferase were 3-5-fold lower, those of aminopeptidase A and endopeptidase-24.11 were 12-15 fold lower, and those of dipeptidyl peptidase IV and aminopeptidase W were 50-70-fold lower. Carboxypeptidase M had a similar activity in both membranes. Alkaline phosphatase and (Na+ + K+)-activated ATPase were more active in the choroid-plexus membranes. No activity for microsomal dipeptidase, aminopeptidase P and carboxypeptidase P could be detected. Six of the peptidases and (Na+ + K+)-activated ATPase were also studied by immunoperoxidase histochemistry at light- and electron-microscopic levels. Endopeptidase-24.11 and (Na+ + K+)-activated ATPase were uniquely located on the brush border, and the other two peptidases appeared to be much more abundant on the endothelial lining of microvessels. Dipeptidyl peptidase IV and aminopeptidase W were also detected in microvasculature. Pial membranes associated with the brain and spinal cord also stained positively for endopeptidase-24.11, aminopeptidase N and peptidyl dipeptidase A. The immunohistochemical studies indicated the subcellular fractionation did not discriminate between membranes derived from epithelial cells (i.e. microvilli) and those from endothelial cells. The possible significance of these studies in relation to neuropeptide metabolism and the control of cerebrospinal fluid production is discussed.
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PMID:Membrane peptidases in the pig choroid plexus and on other cell surfaces in contact with the cerebrospinal fluid. 265 79

Cadmium has been recognized as an environmental contaminant. In oral cadmium intoxication, the immediate target organ is the gastrointestinal tract. The aim of the present work was to study the effect of cadmium on the intestinal absorption of L-threonine and on the aminopeptidase N activity in rabbit jejunum, after in vitro addition and/or oral administration of CdCl2 in drinking water. Results obtained show that cadmium decreases L-threonine absorption in the jejunal tissue. This effect seems to be due to an action mainly on active amino-acid transport at the mucosal border of the intestinal epithelium, because cadmium does not seem to modify the amino-acid diffusion across the intestinal epithelium. Cadmium also inhibits the (Na(+)-K+)-ATPase activity of the enterocyte, which might explain the inhibition of the Na(+)-dependent L-threonine transport. Nevertheless, a direct action of the cadmium ion on the carrier of active transport cannot be rejected. Cadmium modifies the aminopeptidase N activity when administered in drinking water for 4 d.
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PMID:Cadmium action on aminopeptidase N activity and L-threonine intestinal transport in rabbit. 791 22

A short treatment of dog renal brush-border membrane vesicles (BBMV) with sodium cholate, followed by dialysis of the detergent, reorients the polarity of H(+)-ATPase in the membrane and exposes its ATP binding sites to the extravesicular space, as previously shown with pig BBMV. In cholate-pretreated vesicles, the H(+)-ATPase remains fully active, but is inserted under the reversed polarity in sealed vesicles. A large spontaneous N-ethylmaleimide-sensitive ATPase activity is thus observed, as well as a steep intravesicular acidification upon external ATP addition, two findings absent in native vesicles. The ability of nitrate plus ATP to dissociate the hydrolytic subunits ot the proton pump in cholate-pretreated vesicles, but not in native vesicles, demonstrates that most of the ATP binding subunits are accessible to ATP following cholate treatment. The sensitivity of the cytoplasmic domain of the H(+)-ATP activity to trypsin also confirms the reorientation of the enzyme in cholate-pretreated vesicles. The H(+)-ATPase and alkaline phosphatase remain largely associated with the membranes after the treatment with cholate, but gamma-glutamyltranspeptidase, aminopeptidase N, and neutral endopeptidase are largely solubilized. Upon dialysis of cholate, all these enzymes are in part reinserted in the membrane according to their original polarity. The reorientation process is however specific for the H(+)-ATPase. Cholate treatment does not increase the formation of inside-out vesicles. Thus the treatment with cholate really reorients the polarity of the H(+)-ATPase in vesicles and allows for study of the proton pumping capacity of vacuolar H(+)-ATPase of proximal tubules.
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PMID:Effect of cholate on H(+)-ATPase and other proteins of dog renal brush-border membrane. 812 55

Clonal cell lines have been established from primary fetal rat intestinal epithelial cells by stable transfection with plasmids containing either the simian virus 40 (SV40) large T-antigen gene under the control of the heavy metal inducible metallothionein promoter (pMTWt) or the thermolabile SV40 T-antigen gene under the control of the SV40 early promoter (pZipSVtsa58). pMTWt-transfected cells produced sufficient T-antigen to allow them to proliferate both when the metallothionein promoter was induced and uninduced. No differences were observed in the pattern of intestinal epithelial markers expressed when the cells were cultured in the presence or absence of inducing agent (zinc). In contrast, fetal rat intestinal epithelial cells transfected with pZipSVtsa58 were immortalized conditionally; cells proliferated at 32 degrees C but ceased to proliferate between 48 and 72 h of culture at 39 degrees C. Four of these cell lines were characterized in detail; they showed microvilli and tight junctions as well as dome formation and expressed functional and biochemical markers of intestinal epithelial cells, including keratins 8, 19, and 21, aminopeptidase N, and dipeptidyl peptidase IV. One cell line, 2/4/A1, expressed in addition a low level of lactase and sucrase-isomaltase. The amount and/or activity of some of these markers changed during the switch from the proliferative to the nonproliferative state (switch from culture at 32 to 39 degrees C), resulting in a more differentiated phenotype and mimicking similar changes taking place during intestinal epithelial cell differentiation in vivo.
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PMID:Conditionally immortalized intestinal epithelial cells: novel approach for study of differentiated enterocytes. 839 82

Erythromycin has been shown to inhibit the intestinal transport of L-threonine and D-galactose in strips of mucosal jejunum when it was directly added to the incubation medium. Nevertheless, the effect of erythromycin administered therapeutically by intramuscular injection on both the intestinal absorption of nutrients and the intestinal digestive activity, remains unknown. The results obtained show that, firstly, the intestinal absorption of L-threonine is inhibited in animals treated with erythromycin. The kinetic study shows that the effect seems to be mainly due to an alteration of the affinity apparent constant (Kt) of the Na(+)-dependent system of transport located in the mucosal border. However, the Na(+)-dependent L-threonine transport in BBMV was not altered by the treatment with erythromycin. The (Na(+)-K+) ATPase activity in BLMV from treated jejunum was 40% of the activity in control BLMV. Secondly, the treatment with erythromycin did not modify the digestive enzymatic activity of sucrase and aminopeptidase N.
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PMID:Study of the action of intramuscularly administered erythromycin on the L-threonine transport and the digestive enzymatic activity in rabbit jejunum. 876 16

Zinc is a nutritionally essential trace element required for many biological functions to be successfully carried out. The aim of the present work was to study the influence of zinc on the intestinal absorption of L-threonine and on the aminopeptidase N activity in rabbit jejunum, after in vitro addition and/or oral administration of ZnCl2 in drinking water. Results obtained show that zinc decreases L-threonine absorption in the jejunal tissue. This effect would appear to be owing to an action mainly located in active amino acid transport, because zinc does not seem to modify the amino acid diffusion across the intestinal epithelium, of the mucosal border of the intestinal epithelium. Zinc has also been shown to inhibit the (Na(+)-K+)-ATPase activity of the enterocyte, which might explain the inhibition of the L-threonine Na(+)-dependent transport. Nevertheless, a direct action of the zinc on carriers of active transport cannot be rejected. However, zinc did not significantly modify the aminopeptidase N activity in rabbit jejunum.
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PMID:Effect of zinc on aminopeptidase N activity and L-threonine transport in rabbit jejunum. 886 50

Ectopeptidases play important roles in cell activation, proliferation, and communication. Human monocytic cells express considerable amounts of aminopeptidase N/CD13, a transmembrane protein previously proposed to play a role in the regulation of neuropeptides and chemotactic mediators as well as in adhesion and cell-cell interactions. Here, we report for the first time that aminopeptidase N/CD13 in monocytes is partially localized in detergent-insoluble membrane microdomains enriched in cholesterol, glycolipids, and glycosylphosphoinositol-anchored proteins, referred to as "rafts." Raft fractions of monocytes were characterized by the presence of GM1 ganglioside as raft marker molecule and by the high level of tyrosine-phosphorylated proteins. Furthermore, similar to polarized cells, rafts in monocytic cells lack Na(+), K(+)-ATPase. Cholesterol depletion of monocytes by methyl-beta-cyclodextrin greatly reduces raft localization of aminopeptidase N/CD13 without affecting ala-p-nitroanilide cleaving activity of cells.
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PMID:Aminopeptidase N/CD13 is associated with raft membrane microdomains in monocytes. 1069 91

Serotonin has been shown to alter the intestinal transport of ions and intestinal motility. These effects may interfere with each other, modulating the whole physiology of the intestine. We have previously shown that serotonin also alters the transport of nutrients. Thus, the aims of the present work were to determine the possible interference between the secretagogue effect of serotonin and the mechanism by which serotonin inhibits the absorption of nutrients, and to study the effect of serotonin on the digestive activity of nutrients of the brush border membrane jejunum enterocyte in the rabbit. The results show that the secretagogue effect of serotonin neither affects the inhibitory effect of serotonin on the intestinal absorption of the nutrients, nor affects the activity of Na+/K+-ATPase. The activity of sucrase and aminopeptidase N was also not affected by serotonin in the rabbit jejunum. Finally, we also studied different parameters of the motility in the rabbit small intestine. Serotonin seemed to stimulate the motility of the rabbit small intestine by increasing integrated mechanical activity and tone of muscle fibers in duodenum, jejunum, and ileum. In conclusion, serotonin might alter or modulate the whole intestinal physiology.
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PMID:Effects of serotonin on the physiology of the rabbit small intestine. 1084 30

Hypoxic conditions often persist within poorly vascularized tumors. At the cellular level constitutive activation of transcriptional regulators of the hypoxic response leads to the emergence of clones with aggressive phenotypes. The primary interface between the cell and the hypoxic environment is the plasma membrane. A detailed investigation of this organelle is expected to yield further targets for therapeutic perturbation of the response to hypoxia. In the present study, quantitative proteomic analysis of plasma membrane from hypoxia-adapted murine B16F10 melanoma was performed using differential 16O/18O stable isotopic labeling and multidimensional liquid chromatography-tandem mass spectrometry. The analysis resulted in the identification of 24,853 tryptic peptides, providing quantitative information for 2,433 proteins. For a subset of plasma membrane and secreted proteins, quantitative RT-PCR was used to gain further insight into the genomic regulatory events underlying the response to hypoxia. Consistent increases at the proteomic and transcriptomic levels were observed for aminopeptidase N (CD13), carbonic anhydrase IX, potassium-transporting ATPase, matrix metalloproteinase 9, and stromal cell derived factor I (SDF-1). Antibody-based analysis of a panel of human melanoma cell lines confirmed that CD13 and SDF-1 were consistently upregulated during hypoxia. This study provides the basis for the discovery of novel hypoxia-induced membrane proteins.
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PMID:Proteomic analysis of plasma membrane from hypoxia-adapted malignant melanoma. 1708 Oct 51


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