首页    期刊浏览 2025年06月12日 星期四
登录注册

文章基本信息

  • 标题:Calmodulin stimulation of 45Ca2+ transport and protein phosphorylation in cholinergic synaptic vesicles
  • 本地全文:下载
  • 作者:A Rephaeli ; S M Parsons
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:1982
  • 卷号:79
  • 期号:19
  • 页码:5783-5787
  • DOI:10.1073/pnas.79.19.5783
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:Cholinergic synaptic vesicles isolated from the electric organ of Torpedo californica exhibit ATP-dependent uptake of 45Ca2+ that is stimulated by exogenous calmodulin. ATP-independent uptake also occurs, but it is only weakly stimulated by calmodulin. Saturating calmodulin decreased the Michaelis constant for ATP-dependent 45Ca2+ uptake from 52 +/- 0.4 to 12 +/- 0.2 microM and increased the maximal velocity from 3.4 +/- 0.3 to 5.2 +/- 0.5 nmol/mg of protein per min. The dose-response curve for calmodulin-dependent stimulation showed a maximal increase of 3.5-fold in the uptake rate; 0.2 microM calmodulin gave half-maximal stimulation. The activity of the vesicle-associated ATPase was unaffected. Incubation of vesicles with [gamma-32P]ATP and Ca2+ resulted in phosphorylation of four polypeptides of molecular weights about 64,000, 58,000, 54,000, and 41,000 when calmodulin was added. Vesicles that were previously phosphorylated and purified exhibited 2-fold enhanced ATP-independent uptake of 45Ca2+. Cyclic AMP could not substitute for calmodulin. The calcium transport system of the cholinergic synaptic vesicle is regulated by a calcicalmodulin-dependent protein kinase that is vesicle-associated.
国家哲学社会科学文献中心版权所有