Watkins D T, Cooperstein S J
Endocrinology. 1983 Feb;112(2):766-8. doi: 10.1210/endo-112-2-766.
The effects of calcium and calmodulin on the binding of islet secretion granules to plasma membrane vesicles was studied. Free Ca++ (10(-7) to 10(-4) M) produced a concentration-dependent increase in the binding of inside-out. 125I-labeled plasma membrane vesicles to secretion granules; maximum stimulation occurred at 10(-5) M. By contrast, Ca++ had no effect on binding when either inside-out red blood cell or right-side-out islet plasma membrane vesicles were used. Calmodulin (1 microM), in the presence of 10(-4) M Ca++, increased the binding two-fold as compared to Ca++ alone, and trifluoperazine (TFP), and inhibitor of calmodulin, produced a concentration-dependent inhibition of the calmodulin effect. TFP also inhibited the binding produced by 10(-4) M Ca++ in the absence of exogenous calmodulin. These results suggest that Ca++ in the presence of calmodulin modulates the interaction between islet secretion granules and the cytoplasmic surface of the plasma membrane.
研究了钙和钙调蛋白对胰岛分泌颗粒与质膜囊泡结合的影响。游离Ca++（10^(-7)至10^(-4)M）使内翻的、125I标记的质膜囊泡与分泌颗粒的结合呈浓度依赖性增加；最大刺激出现在10^(-5)M时。相比之下，当使用内翻的红细胞或外翻的胰岛质膜囊泡时，Ca++对结合没有影响。在10^(-4)M Ca++存在的情况下，钙调蛋白（1μM）使结合比单独的Ca++增加了两倍，而钙调蛋白抑制剂三氟拉嗪（TFP）产生了浓度依赖性的对钙调蛋白作用的抑制。在没有外源性钙调蛋白的情况下，TFP也抑制了10^(-4)M Ca++产生的结合。这些结果表明，在钙调蛋白存在的情况下，Ca++调节胰岛分泌颗粒与质膜细胞质表面之间的相互作用。
