Leonards K S, Kutchai H
Biochemistry. 1985 Aug 27;24(18):4876-84. doi: 10.1021/bi00339a023.
An essential feature of the function of the Ca2+-ATPase of sarcoplasmic reticulum (SR) is the close coupling between the hydrolysis of ATP and the active transport of Ca2+. The purpose of this study is to investigate the role of other components of the SR membrane in regulating the coupling of Ca2+-ATPase in SR isolated from rabbit skeletal muscle, reconstituted SR, and purified Ca2+-ATPase/phospholipid complexes. Our results suggest that (1) it is possible to systematically alter the degree of coupling obtained in reconstituted SR preparations by varying the [KC1] present during cholate solubilization, (2) the variation in coupling is not due to differences in the permeability of the reconstituted SR vesicles to Ca2+, and (3) vesicles reconstituted with purified Ca2+-ATPase are extensively uncoupled under our experimental conditions regardless of the lipid/protein ratio or phospholipid composition. In reconstituted SR preparations prepared by varying the [KC1] present during cholate treatment, we find a direct correlation between the relative degree of coupling between ATP hydrolysis and Ca2+ transport and the level of the 53-kilodalton (53-kDa) glycoprotein of the SR membrane. These results suggest that the 53-kDa glycoprotein may be involved in regulating the coupling between ATP hydrolysis and Ca2+ transport in the SR.
肌浆网（SR）的Ca2 + -ATP酶功能的一个基本特征是ATP水解与Ca2 +的主动转运之间的紧密偶联。本研究的目的是研究SR膜的其他成分在调节从兔骨骼肌分离的SR、重组SR和纯化的Ca2 + -ATP酶/磷脂复合物中Ca2 + -ATP酶偶联中的作用。我们的结果表明：（1）通过改变胆酸盐溶解过程中存在的[KCl]，有可能系统地改变重组SR制剂中获得的偶联程度；（2）偶联的变化不是由于重组SR囊泡对Ca2 +的通透性差异；（3）在我们的实验条件下，用纯化的Ca2 + -ATP酶重构的囊泡无论脂质/蛋白质比例或磷脂组成如何，都广泛地解偶联。在通过改变胆酸盐处理过程中存在的[KCl]制备的重组SR制剂中，我们发现ATP水解与Ca2 +转运之间的相对偶联程度与SR膜53千道尔顿（53-kDa）糖蛋白的水平之间存在直接相关性。这些结果表明，53-kDa糖蛋白可能参与调节SR中ATP水解与Ca2 +转运之间的偶联。
