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)

We report a method for the isolation of enriched fractions of intact Golgi apparatus from neurons of 10- to 12-day-old rat brains. Neurons were prepared according to a modified method of Farooq and Norton [J. Neurochem. 31, 887-894 (1978)]. Golgi-enriched fractions were obtained after centrifugation of postmitochondrial supernatants in a discontinuous sucrose gradient. Golgi fractions 1 and 2, recovered at the interfaces of 28-34% and 34-36% sucrose densities, respectively, were examined with morphometric and enzymatic methods. Morphometric analyses showed that 21-34% of fraction 1 and 11-29% of fraction 2 consisted of intact Golgi apparatus. Lysosomes, mitochondria, ribosomes, and rough endoplasmic reticulum contaminated fraction 1 (6-10%) and fraction 2 (14-26%). Golgi fraction 1 showed a 25- to 65-fold enrichment over neurons of UDP Gal:GlcNAc galactosyltransferase, CMP-sialic acid:lactosylceramide sialyltransferase, and PAPS:cerebroside sulfotransferase activities. Golgi fraction 2 showed a 8- to 23-fold enrichment over neurons of the activities of the above glycolipid- and glycoprotein-synthesizing enzymes. The activities of the possible marker enzymes rotenone-insensitive NADH-cytochrome c reductase, succinate-cytochrome c reductase, and arylsulfatase were low or minimally elevated in the Golgi fractions. A sevenfold enrichment of Na+, K+-ATPase activities was found in the Golgi fractions. This is consistent either with significant plasma membrane contamination or with the presence of this enzyme in the neuronal Golgi apparatus.
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PMID:Isolation and characterization of an enriched Golgi fraction from neurons of developing rat brains. 400 71

Sodium efflux was studied in 22Na-loaded red blood cells in the presence of arylsulfatase, an enzyme that specifically hydrolyzes sulfatide. Sodium efflux was inhibited in proportion to the amount of arylsulfatase present. Maximum inhibition was almost as high as the efflux obtained in medium with K+ absent. At maximum inhibition 83.2% of the sulfatide content of the fragmented red blood cell membranes was hydrolyzed and ouabain-sensitive (Na+ + K+)-ATPase activity was inhibited by 100%. Sodium efflux, sulfatide content, and (Na+ + K+)-ATPase activity were unaffected with arylsulfatase in the presence of a high concentration of sulfatide. These results indicate that sulfatide plays a specific role in sodium and potassium ion transport. They also suggest that most sulfatide is localized externally in the red blood cell membrane.
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PMID:Sulfatide role in the sodium pump. 627 71

We have characterized sulfate transport in the unicellular green alga Chlamydomonas reinhardtii during growth under sulfur-sufficient and sulfur-deficient conditions. Both the Vmax and the substrate concentration at which sulfate transport is half of the maximum velocity of the sulfate transport (K1/2) for uptake were altered in starved cells: the Vmax increased approximately 10-fold, and the K1/2 decreased approximately 7-fold. This suggests that sulfur-deprived C. reinhardtii cells synthesize a new, high-affinity sulfate transport system. This system accumulated rapidly; it was detected in cells within 1 h of sulfur deprivation and reached a maximum by 6 h. A second response to sulfur-limited growth, the production of arylsulfatase, was apparent only after 3 h of growth in sulfur-free medium. The enhancement of sulfate transport upon sulfur starvation was prevented by cycloheximide, but not by chloramphenicol, demonstrating that protein synthesis on 80S ribosomes was required for the development of the new, high-affinity system. The transport of sulfate into the cells occurred in both the light and the dark. Inhibition of ATP formation by the antibiotics carbonylcyanide m-chlorophenylhydrazone and gramicidin-S and inhibition of either F- or P-type ATPases by N,N-dicyclohexylcarbodiimide and vanadate completely abolished sulfate uptake. Furthermore, nigericin, a carboxylate ionophore that exchanges H+ for K+, inhibited transport in both the light and the dark. Finally, uptake in the dark was strongly inhibited by valinomycin. These results suggest that sulfate transport in C. reinhardtii is an energy-dependent process and that it may be driven by a proton gradient generated by a plasma membrane ATPase.
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PMID:Characterization of Sulfate Transport in Chlamydomonas reinhardtii during Sulfur-Limited and Sulfur-Sufficient Growth. 1223 42


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