Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dicyclohexylcarbodiimide-sensitive ATPase from spinach chloroplast has been isolated. On sodium dodecyl sulfate gels, seven different polypeptides were seen. Five of these polypeptides coincided with the CF1 subunits, a 7,500-dalton peptide was identified as the proteolipid which interacts with [14C]dicyclohexylcarbodiimide, and there was a 15,500-dalton hydrophobic polypeptide with unknown function. In two-dimentional gels, two additional peptides were resolved, one 17,500 daltons (co-migrating in sodium dodecyl sulfate gels with subunit delta) and one 13,500 daltons (co-migrating with subunit epsilon). Reconstitution was obtained by freezing and thawing the complex with a crude mixture of phospholipids. After reconstitution the complex catalyzed 32P1-ATP exchange (rates of 200 to 400 nmoles x mg-1 x min-1) and ATP formation during acid-to-base transition. These reactions were inhibited by dicyclohexylcarbodiimide and uncouplers. Uncouplers at low concentrations stimulated and at high concentrations inhibited the Mg2+-ATPase activity. ATP hydrolysis and 32P1-ATP exchange were catalyzed by the complex in the presence of either Mg2+ or Mn2+ but not with Ca2+ or Co2+. ATP and GTP were substrates for the exchange reaction but not ADP or CTP.
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PMID:Purification and reconstitution of the N,N'-dicyclohexylcarbodiimide-sensitive ATPase complex from spinach chloroplasts. 15 58

We have investigated the localization of a set of intrinsic ATPase activities associated with purified synaptic plasma membranes and consisting of (a) a Mg2+-ATPase; (b) an ATPase active at high concentrations of Ca2+ in the absence of Mg2+ (CaH-ATPase); (c) a Ca2+ requiring Mg2+-dependent ATPase (Ca + Mg)-ATPase, stimulated by calmodulin (Ca-CaM-ATPase); (d) a Ca2+-dependent ATPase stimulated by dopamine (DA-ATPase); and (e) the ouabain-sensitive (Na + K)-ATPase. The following results were obtained: (1) All ATPases are largely confined to the presynaptic membrane; (2) the DA-, (Ca + Mg)-, (Ca-CaM)-, and (Na + K)-ATPases are oriented with their ATP hydrolysis sites facing the synaptoplasm; (3) the Mg- and CaH-ATPases are oriented with their ATP hydrolysis sites on the junctional side of the presynaptic membrane and are therefore classified as ecto-ATPases of as yet unknown function.
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PMID:Localization of endogenous ATPases at the nerve terminal. 629 99

A vesicular fraction isolated from bovine aorta and enriched in fragmented sarcoplasmic reticulum (FSR) exhibited active calcium transport and ATPase activity. By use of a hypotonic NaHCO3 extraction solution, an active preparation was isolated that retained activity for up to 4 days. A small but significant (P less than 0.05) Ca2+-stimulated, Mg2+-dependent ATPase associated with calcium transport was demonstrated with a specific activity of 0.33 mumol inorganic phosphate (Pi).mg-1.min-1. The basal Mg2+ ATPase demonstrated Michaelis-Menten kinetics [Km(Mg2+-ATP) = 0.44 +/- 0.01 X 10(-3) M; Vmax = 2.22 +/- 0.01 mumolPi.mg-1.min-1]. The Ca2+-stimulated, Mg2+-ATPase demonstrated apparent substrate inhibition (Ks approximately 10 mM) with no evidence for end-product (ADP) or excess added Ca2+ contributing to this inhibition. Oxalate-supported active calcium uptake velocities also exhibited quantitatively similar substrate inhibition. These results suggest that FSR from vascular smooth muscle contains either two enzymes or one enzyme with two isomeric forms, one of which is associated with the calcium uptake activity of this structure and the other of unknown function.
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PMID:Influence of ATP on sarcoplasmic reticulum function of vascular smooth muscle. 646 Dec 58

Rim protein (RmP) is an ABC transporter of unknown function in rod outer segment discs. The human gene for RmP (ABCR) is affected in several recessive retinal degenerations. Here, we characterize the ocular phenotype in abcr knockout mice. Mice lacking RmP show delayed dark adaptation, increased all-trans-retinaldehyde (all-trans-RAL) following light exposure, elevated phosphatidylethanolamine (PE) in outer segments, accumulation of the protonated Schiff base complex of all-trans-RAL and PE (N-retinylidene-PE), and striking deposition of a major lipofuscin fluorophore (A2-E) in retinal pigment epithelium (RPE). These data suggest that RmP functions as an outwardly directed flippase for N-retinylidene-PE. Delayed dark adaptation is likely due to accumulation in discs of the noncovalent complex between opsin and all-trans-RAL. Finally, ABCR-mediated retinal degeneration may result from "poisoning" of the RPE due to A2-E accumulation, with secondary photoreceptor degeneration due to loss of the RPE support role.
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PMID:Insights into the function of Rim protein in photoreceptors and etiology of Stargardt's disease from the phenotype in abcr knockout mice. 1041 77

A major mechanism of azole resistance in Candida albicans is overexpression of the genes encoding the ATP binding cassette transporters Cdr1p and Cdr2p due to gain-of-function mutations in Tac1p, a transcription factor of the zinc cluster family. To identify the Tac1p regulon, we analyzed four matched sets of clinical isolates representing the development of CDR1- and CDR2-mediated azole resistance by using gene expression profiling. We identified 31 genes that were consistently up-regulated with CDR1 and CDR2, including TAC1 itself, and 12 consistently down-regulated genes. When a resistant strain deleted for TAC1 was examined similarly, expression of almost all of these genes returned to levels similar to those in the matched azole-susceptible isolate. Using genome-wide location (ChIP-chip) analysis (a procedure combining chromatin immunoprecipitation with hybridization to DNA intergenic microarrays), we found 37 genes whose promoters were bound by Tac1p in vivo, including CDR1 and CDR2. Sequence analysis identified nine new genes whose promoters contain the previously reported Tac1p drug-responsive element (CGGN(4)CGG), including TAC1. In total, there were eight genes whose expression was modulated in the four azole-resistant clinical isolates in a TAC1-dependent manner and whose promoters were bound by Tac1p, qualifying them as direct Tac1p targets: CDR1, CDR2, GPX1 (putative glutathione peroxidase), LCB4 (putative sphingosine kinase), RTA3 (putative phospholipid flippase), and orf19.1887 (putative lipase), as well as IFU5 and orf19.4898 of unknown function. Our results show that Tac1p binds under nonactivating conditions to the promoters of its targets, including to its own promoter. They also suggest roles for Tac1p in regulating lipid metabolism (mobilization and trafficking) and oxidative stress response in C. albicans.
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PMID:Genome-wide expression and location analyses of the Candida albicans Tac1p regulon. 1790 26