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 effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+-adenosine triphosphatase (ATPase) activity in hepatic microsomes was investigated. Mg2+-ATPase activity was clearly increased by the presence of 50 microM Ca2+. Regucalcin (1.0-4.0 microM) caused a remarkable elevation (about 3-fold) of Ca2+-ATPase activity. Also, Mg2+-ATPase activity was increased (about 1.6-fold) by the presence of regucalcin (2.0 and 4.0 microM). Guanosine-5'-O-(3-thiotriphosphate) (GTPrs; 10(-5) and 10(-4) M) and nicotinamide adenine dinucleotide phosphate oxidized form (NADP+; 10(-5) to 10(-3) M) or reduced form (NADPH; 10(-4) and 10(-3) M) significantly increased Ca2+-ATPase activity. These increases were not enhanced by the presence of regucalcin (2.0 microM). Of various metal ions, a comparatively low concentration of V5+ (10(-5) M) or Cd2+ (10(-6) M) significantly increased Ca2+-ATPase activity, while Hg2+, Zn2+, Cu2+ and Mn2+ did not have such an effect. Regucalcin (2.0 microM) did not enhance the effect of V5+ and Cd2+ on Ca2+-ATPase activity. The present finding, that regucalcin activates hepatic microsomal Ca2+-ATPase, suggests a cell physiological role of regucalcin as an activator in the microsomal Ca2+-pump activity. This action of regucalcin may not be influenced by other regulators.
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PMID:Activation of hepatic microsomal Ca2+-adenosine triphosphatase by calcium-binding protein regucalcin. 252 22

A 53,000-dalton intrinsic glycoprotein of the sarcoplasmic reticulum was separated from the Ca2+ + Mg2+-ATPase by dissolution with low concentrations of deoxycholate in the presence of 1 M KCl and purified in two successive gel filtration steps. It was aggregated and eluted at the void volume when subjected to gel filtration in the presence or absence of deoxycholate. When subsequently chromatographed in the presence of sodium dodecyl sulfate, the glycoprotein eluted in pure form as a monomer. The glycoprotein contained 48% nonpolar amino acids. It also contained 4 mol of glucosamine and 18 mol of mannose per mol of protein, suggesting that it contained two chains of (GlcNAc)2, (Man)9. The 53,000-dalton glycoprotein was completely removed from deoxycholate extracts of sarcoplasmic reticulum by affinity chromatography on concanavalin A Sepharose. Elution of glycoproteins with alpha-methyl-D-mannoside and deoxycholate resulted in co-purification of the 53,000-dalton glycoprotein and 160,000-dalton glycoprotein previously observed in sarcoplasmic reticulum. The apparent molecular weight of the glycoprotein was reduced from 53,000 to 49,000 after digestion with endo-beta-N-acetylglucosaminidase H (Endo H) and its reactivity with concanavalin A (Con A) was lost. There was no change in molecular weight of the glycoprotein and no diminution of its reactivity with Con A when sealed vesicles of sarcoplasmic reticulum were treated with Endo H. Endo H reduced the molecular weight and the Con A reactivity of the protein when the vesicles were made permeable by detergents. These observations, together with our previous demonstration that the glycoprotein reacts with a cycloheptaamylose-fluorescamine complex in sealed vesicles (Michalak, M., Campbell, K. P., and MacLennan, D. H. (1980) J. Biol. Chem. 255, 1317-1326), show that the glycoprotein is a transmembrane protein. A protein of approximately 53,000 daltons was labeled when the sarcoplasmic reticulum was reacted with the photoaffinity label [32P]8-N3-cAMP. The labeled protein was neither the glycoprotein nor the high affinity calcium-binding protein since it was not sensitive to Endo H and was sensitive to trypsin digestion.
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PMID:Purification and characterization of the 53,000-dalton glycoprotein from the sarcoplasmic reticulum. 626 Aug 6