Interactions of nucleotide analogues with rod outer segment guanylate cyclase.
Interactions of nucleotide analogues with rod outer segment guanylate cyclase.
复制标题
核苷酸类似物与杆外段鸟苷酸环化酶的相互作用。
DOI：
10.1021/bi00241a016
复制
发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Sharma,RK
中科院分区：
文献类型：
--
作者：
Sitaramayya,A;Marala,RB;Hakki,S;Sharma,RK
摘要：棒材外段环GMP水解的光活化是由一种以gtp结合形式活跃的g蛋白介导的。用不可水解的GTP类似物取代GTP被认为使g蛋白处于持续活化状态，从而延长了环GMP的水解时间。由于GTP是鸟苷酸环化酶的底物，因此细胞中环状GMP浓度的恢复也依赖于GTP，但关于GTP类似物对该酶的影响知之甚少。本文报道了GTP和ATP的类似物作为棒状圆盘膜鸟苷酸环化酶的抑制剂和底物的作用。棒状圆盘膜中GTP合成环状GMP的速率约为50 pmol min （nmol视紫红质）1。GTP和腺嘌呤核苷酸的类似物竞争性地抑制环化酶活性。以镁为金属辅因子时，抑制顺序为ATP> GMP-PNP> AMP-PNP=
Revised Manuscript Received April 18, 1991 abstract: Light activation of cyclic GMP hydrolysis in rod outersegments is mediated by a G-protein which is active in the GTP-bound form. Substitution of GTP with a nonhydrolyzable GTP analogue is thought to leave the G-protein in a persistently activated state, thereby prolonging the hydrolysis of cyclic GMP. Restoration of cyclic GMP concentration in the cell also depends upon GTP since it is the substrate for guanylate cyclase, but little is known about the effects of GTP analogues on this enzyme. We report here the effects of the analogues of GTP and ATP as inhibitors and substrates of rod disk membrane guanylate cyclase. The rate of cyclic GMP synthesis from GTP in rod diskmembranes was about 50 pmol min" 1 (nmol of rhodopsin)" 1. Analogues of GTP and adenine nucleotides competitively inhibited thecyclase activity. The order of inhibition, with magnesium as metal cofactor, was ATP> GMP-PNP> AMP-PNP=