Calcium-independent activation of adenylate cyclase by calmodulin.
Calcium-independent activation of adenylate cyclase by calmodulin.
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钙调蛋白对腺苷酸环化酶的非钙依赖性激活。
DOI：
10.1111/j.1432-1033.1983.tb07423.x
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
J. Wolff
中科院分区：
文献类型：
--
作者：
M. Kilhoffer;G. H. Cook;J. Wolff
百日咳杆菌腺苷环化酶受钙调蛋白通过两种不同的相互作用激活。在低激活剂浓度下(约等于1 nM)，这一过程是钙依赖的(即，在钙调蛋白之前加入EGTA来抑制)。高激活剂浓度(约等于0.1-10微米)在EGTA存在的情况下也能刺激腺苷环化酶，这种作用不能被残留的钙离子或低浓度的钙X钙调蛋白所解释，因此似乎是由于无钙的钙调蛋白所致。一些钙调蛋白剂量-反应曲线显示刺激的两个阶段，被活动平台分开，半最大激活浓度相差100-300倍。这两种作用都是在V上，而不是对ATP的Km上，并且不能被10(5)倍浓度的副蛋白或各种聚阴离子所模拟。此外，在高钙调素浓度下，有EGTA存在时，腺苷环化酶的刺激作用比没有EGTA时更大。1，10-菲咯啉和8-羟基喹啉也能产生这种增强作用，但非螯合异构体不能产生这种增强作用。这些化合物是很差的钙离子螯合剂，在任何钙调素浓度下都有刺激作用(与EGTA不同)，并提示第二种金属离子对这种腺苷环化酶有调节作用。
Adenylate cyclase of Bordetella pertussis is stimulated by calmodulin by two distinct interactions. At low activator concentrations (approximately equal to 1 nM) the process is Ca2+-dependent (i.e. inhibited by EGTA added before calmodulin). High activator concentrations (approximately equal to 0.1-10 microM) stimulate adenylate cyclase also in the presence of EGTA, an effect not accounted for by residual Ca2+ or low concentrations of Ca X calmodulin, which thus appears to be due to calcium-free calmodulin. Some calmodulin dose-response curves show both phases of stimulation, separated by a plateau of activity, and half-maximal activating concentrations differ by 100-300-fold. Both effects are on the V and not the Km for ATP and are not mimicked by 10(5)-fold greater concentrations of parvalbumin or by various polyanions. In addition, adenylate cyclase stimulation at high calmodulin concentrations is greater in the presence of EGTA than in its absence. This enhancement is also produced by 1,10-phenanthroline and 8-hydroxyquinoline but not by non-chelating isomers. These compounds are poor Ca2+ chelators, stimulate at any calmodulin concentration (unlike EGTA), and suggest regulation of this adenylate cyclase by a second metal ion.