Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Separation of the gradient-purified gastric microsome into two membrane subfractions of distinct enzymatic and phospholipid composition has been achieved by mild SDS (0.033% w/v) treatment followed by sucrose gradient centrifugation of the pig and rabbit gastric microsomes. While the high-density membranes had all of the (H+,K+)-ATPase and K+-pNPPase activities and revealed a single major 100-kDa band on SDS-PAGE, the low-density membranes contained all of the 5'-nucleotidase and nearly all of the Mg2+-ATPase. In the present study, the low-density subfraction has been characterized to be derived from the apical membranes and the high-density one from the intracellular tubulovesicular membranes of the parietal cells. Such characterization was based primarily on sole dependency of the apical plasma membranes on the endogenous activator for (H+,K+)-ATPase activity, differential sensitivity of the activator (AF)-dependent and -independent (H+,K+)-ATPase on micromolar vanadate and Ca2+, specific vitamin B12 binding ability of the apical plasmalemma, phospholipid and protein profiles of the two membrane subfractions, and other parameters. The AF, mentioned previously, has recently been implicated as a cytosolic regulator of the gastric (H+,K+)-ATPase [Bandopadhyay et al. (1987) J. Biol. Chem. 262, 5664-5670]. Two different forms (i.e., AF-dependent and -independent forms) of the (H+,K+)-ATPase are suggested to be present in the tubulovesicles on the basis of differential vanadate sensitivity while the AF-dependent form alone is present in the apical membranes. The data have been discussed in terms of stimulation-induced membrane transformation characteristic of the H+-secreting epithelia including the acid-secreting cells of the stomach.
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PMID:Characteristics of the isolated apical plasmalemma and intracellular tubulovesicles of the gastric acid secreting cells: demonstration of secretagogue-induced membrane mobilization. 285 60

The fes mutation in Escherichia coli K12, which inactivates enterochelin esterase, allows the cell to accumulate ferric enterochelin. The ferric complex of enterochelin was released in significant quantities from a fes mutant after osmotic shock. Analysis of the effects of the individual stages of the shock procedure in wild-type cells showed that prior exposure of cells to sucrose and EDTA was not required, careful dilution of cells into a hypo-osmolar medium being sufficient to induce efflux of Fe3+. Prior treatment with EDTA or exposure to shearing forces served either to enhance efflux or to induce efflux in isotonic media. Neither vitamin B12 nor 5'-nucleotidase was released from the periplasm by these procedures. The release observed under mild conditions was stimulated specifically by Co2+, did not occur at 0 degree C, and was inhibited by 2,4-dinitrophenol at 37 degrees C. From these observations, it was concluded that the efflux of Fe3+ represents a physiological response of the cell to exposure to a hypo-osmolar medium. Such changes may enhance survival following physicochemical stressing of the bacterial outer membrane.
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PMID:Effect of osmotic shock and shearing forces on ferric enterochelin transport in Escherichia coli K12. 295

Highly sensitive techniques have been used for the assay of a range of marker enzymes including lactase, sucrase, alkaline phosphatase, leucyl-beta-naphthylamidase (brush border), and 5'-nucleotidase (basolateral membrane) in jejunal biopsy homogenates from patients with adult coeliac disease with and without steatorrhoea and from a control group. The absorption of D-xylose and vitamin B12 was compared in the two groups with coeliac disease. All enzymes assayed were equally depressed in both groups of coeliac disease as compared with the controls. The absorption of D-xylose and vitamin B12 were reduced in the patients with steatorrhoea compared with those without steatorrhoea. The findings suggest that lack of steatorrhoea in some patients with coeliac disease is due to better preservation of the ileal function rather than to a less severe jejunal mucosal injury.
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PMID:Enzyme activities in jejunal biopsy samples from patients with adult coeliac disease with and without steatorrhoea. 632 31