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)

The immunosuppressive effects of the dunaimycins, a new complex of spiroketal 24-membered macrolides, were compared to cyclosporin A, ascomycin, and rapamycin. Each dunaimycin was a potent inhibitor of the mitogenic response observed in mixed murine splenocyte or human leukocyte cultures, and like immunosuppressive drugs these compounds were relatively less potent inhibitors of the constitutive proliferation of murine EL4 thymoma cells. Dunaimycin D4S showed no selectivity in inhibiting the mitogenic response of spleen cells to concanavalin A, pokeweed mitogen, lipopolysaccharide, or phytohemagglutinin. Cyclosporin A and ascomycin did not inhibit interleukin 2 dependent proliferation, whereas the dunaimycins and rapamycin blocked the uptake of [3H]thymidine in mixed cultures supplemented with exogenous interleukin 2. In addition, dunaimycin D4S had no apparent affinity for cyclosporin A or FK-506 immunophilins. Although the dunaimycins inhibited the activity of Na+, K(+)-ATPase, inhibition of this enzyme appeared insufficient to explain the biological activity of these new macrolides. Over a narrow concentration range, dunaimycin D4S showed in vivo immunosuppressive activity in the murine popliteal lymph node hyperplasia model.
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PMID:Dunaimycins, a new complex of spiroketal 24-membered macrolides with immunosuppressive activity. III. Immunosuppressive activities of dunaimycins. 172 3

Purified plasma membranes of mouse EL4 lymphoma cells were fractionated by means of affinity chromatography on concanavalin A-Sepharose into two subfractions; one (MF1) eluted freely from the affinity column, the second (MF2) adhered specifically to Con A-Sepharose. Both membrane subfractions proved to be of plasma membrane origin, as evidenced by the following criteria. (i) The ratio of cholesterol to phospholipid was nearly identical in plasma membrane and both subfractions. (ii) When isolated plasma membranes were labelled with tritiated NaBH4, both subfractions exhibited identical specific radioactivities. (iii) After enzymatic radioiodination of the cells, the total content of labelled proteins was very similar in isolated plasma membranes and in both subfractions. (iv) Some plasma membrane marker enzymes exhibited nearly identical specific activities in plasma membranes, MF1 or MF2 including gamma-glutamyl transpeptidase, 5'-nucleotidase and Mg2+-ATPase. Both subfractions exhibited characteristic differences. Thus the specific activities of (Na+ + K+)-ATPase, Ca2+-ATPase and lysophosphatidylcholine acyltransferase were several-fold enriched in MF2 compared to MF1. SDS-polyacrylamide gel electrophoresis revealed a different polypeptide composition of the two subfractions. Polypeptides of apparent molecular mass of 116, 95, 42, 39, 30 and 28 kDa were highly enriched in MF2, whereas MF1 contained another set of proteins, of apparent molecular mass of 70, 55 and 24 kDa. The phospholipid fatty acid composition of the subfractions proved to be different, as well, MF2 contained more saturated fatty acids than MF1. The data suggest the existence of plasma membrane domains in the plasma membranes of the mouse EL4 lymphoma cells, containing a set of polypeptides, among others membrane bound enzymes, embedded in a different phospholipid milieu.
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PMID:Characterization of plasma membrane domains of mouse EL4 lymphoma cells obtained by affinity chromatography on concanavalin A-Sepharose. 407 40

The fatty acid composition of plasma membrane phospholipids of the murine T lymphocyte tumor EL4 were systematically modified in an attempt to understand the relationship between lipid bilayer composition and plasma membrane physical and biological properties. Two plasma membrane enzyme activities, adenylate cyclase and ouabain-sensitive (Na+ + K+)-ATPase, were measured in normal and fatty acid-substituted EL4 plasma membrane fractions. The fatty acid effect on enzyme activities was similar to previously reported effects of fatty acids on cytotoxic T cell function. The activity of both enzymes was inhibited by saturated fatty acids, while unsaturated fatty acids had a moderate enhancing effect on both enzyme activities. Using two different nitroxide derivatives of stearic acid, the order parameter and approximate rotational correlation times were calculated from ESR spectra of normal and fatty acid-modified plasma membranes. No significant differences was found in either parameter in these membranes. These results, in conjunction with earlier data from our laboratory and others, suggest that caution should be exercised in inferring changes in membrane 'fluidity' based on lipid modulation of biological membranes.
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PMID:The relationship between plasma membrane lipid composition and physical-chemical properties. II. Effect of phospholipid fatty acid modulation on plasma membrane physical properties and enzymatic activities. 627 60