Vincenzi F F, Hinds T R, Raess B U
Ann N Y Acad Sci. 1980;356:232-44. doi: 10.1111/j.1749-6632.1980.tb29614.x.
The data summarized and presented in this paper are consistent with the interpretation that CaM participates in the regulation of the plasma membrane calcium pump. Certain drugs, such as phenothiazines can antagonize CaM. Ca2+ loading of RBCs promotes CaM binding to RBC membranes and results in decreased responsiveness of the [Ca2+ + Mg2+)-ATPase to CaM. The latter effect may be mediated by a Ca2+ activated transglutaminase. Activation of (Ca2+ + Mg2+)-ATPase by CaM in vitro was shown not to be instantaneous, probably because of slow binding. CaM binding to isolated RBC membranes exhibits a Ca2+ dependence that is similar to that for activation of the (Ca2+ + Mg2+)-ATPase, and CaM binding does not decrease at high [Ca2+]s. Calculations based on assumed values for RBC [Ca2+], [CaM], and binding affinities of Ca2+ for CaM and CaM(Ca2+)n for the Ca2+ pump ATPase resulted in the tentative conclusion that most pump sites are occupied by CaM in the RBC in vivo. This conclusion, and the relatively slow time course of the CaM effect on (Ca2+ + Mg2+)-ATPase prompt us to suggest that, for all practical purposes, CaM is a subunit of the Ca2+ pump ATPase in vivo.
本文总结并呈现的数据与钙调蛋白（CaM）参与质膜钙泵调节的解释一致。某些药物，如吩噻嗪类药物可拮抗钙调蛋白。红细胞（RBC）的Ca2+负载促进钙调蛋白与红细胞膜结合，并导致（Ca2+ + Mg2+）-ATP酶对钙调蛋白的反应性降低。后一种效应可能由Ca2+激活的转谷氨酰胺酶介导。体外实验表明，钙调蛋白对（Ca2+ + Mg2+）-ATP酶的激活并非瞬间发生，可能是由于结合缓慢。钙调蛋白与分离的红细胞膜结合表现出与（Ca2+ + Mg2+）-ATP酶激活相似的Ca2+依赖性，且在高Ca2+浓度下钙调蛋白结合并不减少。基于红细胞Ca2+、钙调蛋白的假设值以及Ca2+对钙调蛋白和钙调蛋白（Ca2+）n对钙泵ATP酶的结合亲和力进行的计算得出初步结论，即体内红细胞中大多数泵位点被钙调蛋白占据。这一结论以及钙调蛋白对（Ca2+ + Mg2+）-ATP酶作用的相对缓慢的时间进程促使我们提出，实际上，钙调蛋白在体内是钙泵ATP酶的一个亚基。
