Cavaggioni A, Sorbi R T
Proc Natl Acad Sci U S A. 1981 Jun;78(6):3964-8. doi: 10.1073/pnas.78.6.3964.
Physiological concentrations of cyclic guanosine 3',6'-monophosphate (cGMP) inhibit 45Ca uptake and increase 45Ca release from vertebrate photoreceptor rod outer segment disc membranes. These effects are specific for cGMP. Several facts, including the independence of these effects from added triphosphates, suggest that cGMP diminishes the Ca-binding capacity of the disc membranes. Preliminary data show that the apparent affinity constant of the cGMP-dependent Ca-binding sites of the disc membranes is of the same (or even higher) order of magnitude as that of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. As expected, the observed cGMP effects are not dependent on the light or dark conditions of the disc membranes.
环鸟苷 3',6'-单磷酸(cGMP)的生理浓度可抑制 45Ca 的摄取,并增加 45Ca 从脊椎动物光感受器视杆外段盘膜的释放。这些作用对 cGMP 具有特异性。包括这些作用不依赖于添加的三磷酸酯在内的几个事实表明,cGMP 降低了盘膜的钙结合能力。初步数据显示,盘膜中 cGMP 依赖性钙结合位点的表观亲和常数与乙二醇双(β-氨基乙醚)-N,N,N',N'-四乙酸的表观亲和常数处于相同(甚至更高)的数量级。正如预期的那样,观察到的 cGMP 作用不依赖于盘膜的光照或黑暗条件。