Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q3SYG4 (C18)
 23,707 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of glucose and oxygen on the formation of the plasma membrane of Staphylococcus aureus were studied. Phospholipids were consistent components of the membrane and were not affected by glucose or oxygen. Phospholipid fatty acids in cells grown in glucose containing media were rich in Ceven (C18, C20) fatty acid chains, whereas cells grown in glucose deficient media (normal broth) had anteiso Codd (C15,C17) fatty acid chains in place of Ceven chains. This may indicate increased membrane rigidity of the cells grown in glucose containing media. Cytochromes and ATPase were present in the membrane from cells grown in normal broth, but were deficient in the cells grown in glucose containing media. Polypeptide analysis of the membrane proteins showed a deficiency of the bands corresponding to these enzymes. They were not induced by the additionof oxygen to cells grown in glucose containing media. It was concluded that glucose was the dominant factor inhibiting the formation of these membrane enzymes.
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PMID:Effect of glucose and oxygen on the structure of the plasma membrane of Staphylococcus aureus. 16 Jan 85

Temperature-responsive microsomes of the ciliate protozoan Tetrahymena have been originally fractionated by step centrifugation on two-layered, Mg2+-containing sucrose gradients. Three fractions have been obtained, which are termed smooth I, smooth II and rough according to the appearance of the membrane vesicles upon electron-microscopy. Smooth I, smooth II, and rough microsomes exhibit RNA/protein ratios of 0.09, 0.20, and 0.34; their phospholipid/protein ratios and their neutral lipid/phospholipid ratios were 0.52, 0.43 and 0.25, and 0.17, 0.18 and 0.13, respectively. All three fractions contain equivalent, low succinic dehydrogenase and 5'-nucleotidase activities. Glucose-6-phosphatase and acid phosphatase are more concentrated in smooth I membranes than in rough membranes. The reverse is true for ATPase. The smooth II membranes occupy an intermediate position except that their ATPase activity is the lowest of the three fractions. The specific activities of these enzymes of the three microsomal fractions are compared to those of homogenates of whole cells. Thin-layer chromatography reveals a very similar polar and nonpolar lipid pattern of the three microsomal fractions. The major phospholipid compounds are phosphatidlethanolamine, glycerideaminoethylphosphonate and phosphatidylcholine, while diglycerides, an unknown NL-compound, and triglycerides are the major apolar lipids. Gas liquid chromatography shows that the fatty acids are mainly even-numbered ranging between C12 and C18. The smooth I, smooth II and rough membranes contain 65.2, 69.3 and 72.7% unsaturated fatty acids in their polar lipids, whereas only 52.7, 49.7 and 48.3% unsaturated acids are found in their apolar lipids, respectively. The fatty acids are more unevenly distributed among the individual polar lipids than in the apolar ones.
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PMID:Membranes of Tetrahymena. IV. Isolation and characterization of temperature-responsive smooth and rough microsomal subfractions. 17 62

We measured the concentration of endogenous digitalis-like factors (EDLFs) in milk or colostrum of women during nursing on different days after delivery. EDLF concentrations were assayed by a solid-phase RIA involving antidigoxin antibodies and by a radioreceptor assay (RRA) involving human placenta Na+/K(+)-ATPase. The mean (SD) EDLF concentrations as measured by RIA were 35.6 (19.4) ng of digoxin equivalents per liter in milk samples (n = 37) and 61.3 (12.5) ng/L in colostrum samples (n = 5); the mean EDLF concentration as measured by RRA in milk samples (n = 11) was 573 (717) ng/L (range 0-2098). EDLF concentration in milk is greater than circulating concentrations in healthy adults but is comparable with serum concentration in the third trimester of pregnancy. In milk and serum samples (n = 8) collected at the same time, heating and (or) extracting with Sep-Pak C18 cartridges before the RIA produced significantly different EDLF values from those in untreated serum (P less than 0.001) and milk (P = 0.035). EDLF in milk appeared to be not bound or weakly bound to milk protein, as indicated by the fact that boiling did not increase the digoxin-like immunoreactivity.
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PMID:Endogenous digitalis-like factors in human milk. 131 18

We examined the hypothesis that hypothalamo-hypophysial tissue contains an endogenous Na pump inhibitor. From bovine posterior pituitary, we purified a substance which inhibits Rb uptake by human erythrocytes. This inhibitory activity was found in the eluate of 10% acetonitrile from a C18 flash column and purified by subsequent three steps of reversed-phase high-performance liquid chromatography (HPLC). Sequence analysis revealed that this substance was identical to joining peptide, one of the major products of proopiomelanocortin (POMC). This peptide had hypertensive and tachycardiac effects in spontaneously hypertensive rats (SHR) after central administration, with weak Na,K-ATPase inhibitory activity (IC50 = 0.5 mM).
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PMID:A Na pump inhibitor from bovine posterior pituitary: purification, structure determination and its cardiovascular effect in rat. 133 44

The ATPase activity for the (Ca2(+)-Mg2+)-ATPase purified from rabbit skeletal muscle sarcoplasmic reticulum is lower when reconstituted into bilayers of dimyristoleoylphosphatidylcholine [(C14:1)PC] than when it is reconstituted into dioleoylphosphatidylcholine [(C18:1)PC]. The rate of formation of phosphoenzyme on addition of ATP is slower for (C14:1)PC-ATPase than for the native ATPase or (C18:1)PC-ATPase. The reduction in rate of phosphoenzyme formation is attributed to a reduction in the rate of a conformational change on the ATPase following binding of ATP but before phosphorylation. The level of phosphoenzyme formed from Pi is also less for (C14:1)PC-ATPase than for (C18:1)PC-ATPase. At steady state at pH 6.0 in the presence of ATP Ca2+ is released from (C18:1)PC-ATPase into the medium, but not from (C14:1)PC-ATPase. These effects of (C14:1)PC on the ATPase are reversed by addition of androstenol to a 1:1 molar ratio with (C14:1)PC. The results are interpreted in terms of a kinetic model for the ATPase.
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PMID:Effects of phospholipids on the function of (Ca2(+)-Mg2+)-ATPase. 182 18

An enriched plasma membrane fraction was isolated from caput, corpus, and cauda rat spermatozoa and analyzed for lipid and protein content, thermal phase transition temperature using electron paramagnetic resonance spectroscopy (EPR), and enzymatic assays of calcium-dependent ATPase activity. Based on sperm concentration, total membrane phospholipid, cholesterol, and protein content declined as sperm passed through the epididymis. A more refined analysis of the bulk plasma membrane phospholipid revealed that approximately 56% of the phospholipid consisted of choline (PC) and ethanolamine (PE) phosphoglycerides; the remainder consisted of sphingomyelin (SM), phosphatidylserine (PS), and diphosphatidylglycerol (DPG). The mole percent of PE increased in sperm proceeding from the caput to the corpus epididymis and then declined from the corpus to the cauda epididymis. The phospholipid-bound fatty acids consisted primarily of palmitate (C16:0) and stearate (C18:0), with a significant increase in the mole percent of the docosapentenoyl acyl group (C22:5) in cauda sperm. Arrhenius' plots of the EPR peak height signals using the lipid soluble spin label, 5-doxyldecane, and the calcium-dependent ATPase activity as a function of temperature demonstrated a change in the apparent fluidity of the membrane and energy of activation of the calcium-dependent ATPase associated with the three sperm membrane preparations. These data suggest that the apparent fluidity and biochemical composition of the sperm membrane change during epididymal maturation.
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PMID:Correlation between changes in rat sperm membrane lipids, protein, and the membrane physical state during epididymal maturation. 184 30

The fluorescence quenching properties of a brominated derivative of androstenol 5 alpha,6 beta-dibromoandrostan-3 beta-ol have been used to study binding to phospholipid bilayers and to the (Ca2+ + Mg2+)-ATPase purified from sarcoplasmic reticulum of rabbit skeletal muscle. It is shown that androstenol is excluded from the phospholipid/protein interface of the ATPase but can bind to other (non-annular sites) on the ATPase. Binding to these sites increases in strength with decreasing chain length for the phospholipids present in the system. Binding is also stronger in the presence of phospholipids in the gel phase than in the liquid crystalline phase. Androstenol increases the ATPase activity of the ATPase reconstituted with phosphatidylcholines of chain lengths less than C18, but has no effect on activity for the ATPase reconstituted with phosphatidylcholines of chain lengths C18 or greater. The effects of cholestanols on the activity of the ATPase reconstituted with dimyristoleoylphosphatidylcholine depend on the configuration of the sterol, with 5 alpha-cholestan-3 alpha-ol having little effect but the other isomers causing a marked stimulation.
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PMID:Structural effects on the interaction of sterols with the (Ca2+ + Mg2+)-ATPase. 214 39

The (Ca2(+)-Mg2(+)-ATPase purified from skeletal muscle sarcoplasmic reticulum binds two Ca2+ ions per ATPase molecule. On reconstitution into bilayers of dioleoylphosphatidylcholine [C18:1)PC) or dinervonylphosphatidylcholine [C24:1)PC) the stoichiometry of binding remains unchanged, but when the ATPase is reconstituted into bilayers of dimyristoleoylphosphatidylcholine [C14:1)PC) the stoichiometry changes to one Ca2+ ion per ATPase molecule. Nevertheless, the level of phosphorylation is the same for the ATPase reconstituted with (C18:1)PC or (C14:1)PC. The effect of (C14:1)PC on the stoichiometry of Ca2+ binding is prevented by androstenol at a 1:1 molar ratio with the phospholipid.
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PMID:Effects of phospholipids on binding of calcium to (Ca2(+)-Mg2(+)-ATPase. 214 65

Endogenous digitalis-like factors (DLF) including those which were immunoreactive with digoxin antibody and those which displaced ouabain from Na,K-ATPase, were isolated from the plasma of a dialysis-dependent male patient not taking digoxin. Plasma was passed through a C18 disposable column, the DLF eluted with methanol and separated by HPLC on a C8 column. Immunoreactive DLF were measured in each 1 ml HPLC fraction using radioimmunoassay (RIA) for digoxin. The immunoreactive peaks were determined and aliquots from each peak analyzed by fast atom bombardment mass spectroscopy (FAB-ms). The compounds in the five major HPLC immunoreactive peaks were identified as: 1) dehydroepiandrosterone glucuronide and tetrahydrocortisone glucuronide; 2) epiandrosterone glucuronide; 3) dehydroepiandrosterone sulfate and androsterone glucuronide; 4) epiandrosterone sulfate and 5) androsterone sulfate and androstanediol glucuronide. These immunoreactive DLF represent 70% of the total plasma immunoreactive DLF of 0.124 micrograms digoxin equivalents/l. Aliquots of the HPLC fractions were also assayed for ability to displace ouabain from Na,K-ATPase. The ouabain displacing DLF gave a very different elution pattern from that obtained by RIA with the major Na,K-ATPase ouabain displacing DLF eluting in the more polar fractions. They remain unidentified.
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PMID:Plasma conjugated androgens in a dialysis-dependent male as immunoreactive digitalis-like factors. 217 21

Adenosinetriphosphopyridoxal (AP3PL) specifically modifies Lys684 of Ca2(+)-ATPase of sarcoplasmic reticulum (SR-ATPase) in the presence of Ca2+, leading to its inactivation (Yamamoto, H. et al. (1988) J. Biochem. 103, 452-457). We have now investigated the effects of AP3PL on SR-ATPase in the absence of Ca2+. Similarly to its action in the presence of Ca2+, AP3PL inhibited the Ca2(+)-transporting activity in a dose-dependent manner in the absence of Ca2+ as well. ATP and ADP protected SR-ATPase against inactivation by this reagent. One mole of AP3PL was bound per mol of SR-ATPase with concomitant loss of the Ca2(+)-transporting activity. Binding of AP3PL to SR-ATPase was prevented by ATP. AP3PL-labeled SR membranes were digested with thermolysin and labeled thermolytic peptides were purified through C18 reversed-phase HPLC. Two major AP3PL-labeled peptides were obtained in approximately 1:1 ratio; one was an octapeptide corresponding to 679-ValGluProSerHisLys*SerLys-686, and the other, a nonapeptide corresponding to 487-PheSerArgAspSerLys*ArgMetSer-495 (Lys* indicates a labeled Lys residue) of SR-ATPase. Lys684 in the former turned out to be the same as the highly specific target of AP3PL in the presence of Ca2+ which was identified previously. The target site specificity of AP3PL thus changed significantly but not entirely on binding of Ca2+ to SR-ATPase. This indicates that the spatial arrangement around the gamma-phosphoryl group of the bound ATP is affected by Ca2+ ions bound at the transport site. It is also likely that Lys492 and Lys684 are situated close together in the ATP binding site of SR-ATPase.
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PMID:Ca2(+)-dependent conformational change of the ATP-binding site of Ca2(+)-transporting ATPase of sarcoplasmic reticulum as revealed by an alteration of the target-site specificity of adenosine triphosphopyridoxal. 253 25


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