{"title":"Invariance of stoichiometry of the sarcoplasmic reticulum calcium pump at physiological calcium concentrations--a reevaluation.","authors":"W Hasselbach, A Migala","doi":"10.1515/znc-1985-7-821","DOIUrl":null,"url":null,"abstract":"<p><p>The decline of the transport ratio of the sarcoplasmic calcium pump observed in a recent study (A. Gafni and P. D. Boyer, Proc. Natl. Acad. Sci. USA 82, 89-101 [1985] ) results from the retardation of calcium oxalate precipitation at low calcium/protein ratios. The prevailing high internal calcium level supports a rapid calcium backflux and a compensatory ATP hydrolysis during net calcium uptake which reduces the transport ratio. Yet, the determined calcium backflux does not fully account for the decline of the transport ratio. A supposed modulation of the stoichiometry of the pump by external calcium (0.1 microM) is at variance with results of previous studies showing a constant transport ratio of two in the same calcium concentration range.</p>","PeriodicalId":23914,"journal":{"name":"Zeitschrift fur Naturforschung. Section C, Biosciences","volume":"40 7-8","pages":"571-5"},"PeriodicalIF":0.0000,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/znc-1985-7-821","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Zeitschrift fur Naturforschung. Section C, Biosciences","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1515/znc-1985-7-821","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 3
Abstract
The decline of the transport ratio of the sarcoplasmic calcium pump observed in a recent study (A. Gafni and P. D. Boyer, Proc. Natl. Acad. Sci. USA 82, 89-101 [1985] ) results from the retardation of calcium oxalate precipitation at low calcium/protein ratios. The prevailing high internal calcium level supports a rapid calcium backflux and a compensatory ATP hydrolysis during net calcium uptake which reduces the transport ratio. Yet, the determined calcium backflux does not fully account for the decline of the transport ratio. A supposed modulation of the stoichiometry of the pump by external calcium (0.1 microM) is at variance with results of previous studies showing a constant transport ratio of two in the same calcium concentration range.
最近的一项研究(a . Gafni和P. D. Boyer, Proc. Natl)观察到肌浆钙泵运输比率的下降。学会科学。(USA 82, 89-101[1985])是由于低钙/蛋白比时草酸钙沉淀的延迟。在净钙摄取过程中，普遍存在的高内部钙水平支持快速的钙回流和代偿性ATP水解，从而降低了运输比。然而，测定的钙回流并不能完全解释输运比的下降。外界钙(0.1微米)对泵的化学计量的假设调制与先前的研究结果不同，这些研究显示在相同的钙浓度范围内恒定的输运比为2。
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