Regulation of deactivation of photoreceptor G protein by its target enzyme and cGMP.
Regulation of deactivation of photoreceptor G protein by its target enzyme and cGMP.
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通过其靶酶和CGMP对光感受器G蛋白的失活调节。
DOI：
10.1038/357416a0
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发表时间：
1992-06-04
期刊：
影响因子：
64.8
通讯作者：
Bownds MD
中科院分区：
文献类型：
--
作者：
Arshavsky VYu;Bownds MD
光感受器G蛋白，即转导蛋白，是一类异三聚体G蛋白中的一种，在膜受体和细胞内酶或离子通道之间起中介作用。光激活的视紫红质在多个转导蛋白分子上催化GDP交换GTP。激活的转导蛋白通过释放磷酸二酯酶γ-亚基的抑制作用刺激环GMP磷酸二酯酶。这导致杆状细胞中cGMP水平的降低，以及由cGMP - 1控制的质膜阳离子通道的关闭。在这种和其他系统中，关闭反应需要GTP结合到G蛋白上，通过内在的GTP酶活性水解5 - 7。在这里，我们报道了转导蛋白与cGMP磷酸二酯酶的相互作用，特别是与其γ-亚基的相互作用，使GTPase活性提高了几倍。因此，磷酸二酯酶的γ-亚基的功能类似于调节小gtp结合蛋白类的gtpase激活蛋白。cGMP可能通过磷酸二酯酶α和β-亚基的非催化cGMP结合位点部分抑制这种加速。这种cGMP调节可能在光响应的光适应中发挥作用，作为一种负反馈，由于光导致细胞质cGMP减少，减少了活化的cGMP磷酸二酯酶的寿命。
THE photoreceptor G protein, transducin, is one of the class of heterotrimeric G proteins that mediates between membrane receptors and intracellular enzymes or ion channels. Light-activated rhodopsin catalyses the exchange of GDP for GTP on multiple transducin molecules. Activated transducin then stimulates cyclic GMP phosphodiesterase by releasing an inhibitory action of the phosphodiesterase γ-subunits. This leads to a decrease in cGMP levels in the rod, and closure of plasma membrane cationic channels gated by cGMP1–4. In this and other systems, turn-off of the response requires the GTP bound to G protein to be hydrolysed by an intrinsic GTPase activity5–7. Here we report that the interaction of transducin with cGMP phosphodiesterase, specifically with its γ-subunits, accelerates GTPase activity by several fold. Thus the γ-subunits of the phosphodiesterase serve a function analogous to the GTPase-activating proteins that regulate the class of small GTP-binding proteins. The acceleration can be partially suppressed by cGMP, most probably through the non-catalytic cGMP-binding sites of phosphodiesterase α and β-subunits. This cGMP regulation may function in light-adaptation of the photo-response as a negative feedback that decreases the lifetime of activated cGMP phosphodiesterase as light causes decreases in cytoplasmic cGMP.
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影响因子：
64.8
作者：
KUHN, H
通讯作者：
KUHN, H
DOI：
10.1073/pnas.87.1.288
发表时间：
1990-01-01
影响因子：
11.1
作者：
CHARBONNEAU, H;PRUSTI, RK;BEAVO, JA
通讯作者：
BEAVO, JA
影响因子：
3.5
作者：
ARSHAVSKY, VY;ANTOCH, MP;PHILIPPOV, PP
通讯作者：
PHILIPPOV, PP
影响因子：
56.9
作者：
SIMON, MI;STRATHMANN, MP;GAUTAM, N
通讯作者：
GAUTAM, N
DOI：
10.1073/pnas.86.13.4922
发表时间：
1989-07-01
影响因子：
11.1
作者：
BROWN, RL;STRYER, L
通讯作者：
STRYER, L