Okabe T, Sugimoto N, Matsuda M
Department of Tuberculosis Research, Osaka University, Japan.
Biochem Biophys Res Commun. 1992 Jul 31;186(2):1006-11. doi: 10.1016/0006-291x(92)90846-d.
The role of calmodulin in exocytotic secretion was studied using digitonin-permeabilized bovine adrenal medullary chromaffin cells. Addition of calmodulin to the permeabilized cells increased Ca(2+)-dependent norepinephrine release in a dose-dependent manner. Unlike calmodulin, addition of caldesmon, actin or bovine serum albumin did not increase the release. Calmodulin increased the release at Ca2+ concentrations of more than 10(-6) M and its effect increased with increase in Mg2+ concentration. Th release of norepinephrine enhanced by calmodulin was inhibited by tetanus toxin, which specifically inhibits exocytotic secretion. These results indicate directly that calmodulin plays an important role in exocytotic secretion from chromaffin cells.
利用洋地黄皂苷通透处理的牛肾上腺髓质嗜铬细胞研究了钙调蛋白在胞吐分泌中的作用。向通透处理的细胞中添加钙调蛋白会以剂量依赖的方式增加钙离子依赖的去甲肾上腺素释放。与钙调蛋白不同，添加钙调蛋白结合蛋白、肌动蛋白或牛血清白蛋白并不会增加释放量。钙调蛋白在钙离子浓度高于10⁻⁶ M时会增加释放量，并且其作用会随着镁离子浓度的增加而增强。钙调蛋白增强的去甲肾上腺素释放受到破伤风毒素的抑制，破伤风毒素特异性抑制胞吐分泌。这些结果直接表明钙调蛋白在嗜铬细胞的胞吐分泌中起重要作用。
