Light and dark active phosphodiesterase regulation in salamander rods.
Light and dark active phosphodiesterase regulation in salamander rods.
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DOI：
10.1085/jgp.98.3.575
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发表时间：
1991-09
影响因子：
3.8
通讯作者：
COBBS, WH
中科院分区：
文献类型：
--
作者：
COBBS, WH
我们研究了3 '，5'-环鸟苷一磷酸（cGMP）磷酸二酯酶（PDE）的激活，通过使用细胞渗透性酶抑制剂。将在抽吸电极中保持的虎钝口鱼的棒跳入0.01-1 mM的3-异丁基-1-甲基黄嘌呤（IBMX）的流中。初始瞬态光敏电流符合这样的概念，即黑暗和光激活形式的PDE独立地促进代谢活性，并且被IBMX等效地抑制（表观Ki 30微米）。抑制在50 ms内发展，产生酶速度的阶跃降低，这可以通过闪光或光的阶跃激活来抵消。暗PDE活性相当于1，000个异构化棒-1s-1的酶的光活化，足以在0.6 s内水解游离cGMP池（1/e）。稳态光激活PDE的异构化速率与光激活PDE的异构化速率成线性关系，从黑暗到电流饱和的范围增加了10倍。抑制剂和光照同时开始以不产生膜电流净变化的条件定义了光活化PDE的表观寿命，TPDE* = 0.9 s，其在0-3 × 10（5）异构化s-1范围内（50 - 0 pA）与背景光照和电流无关。适应是一个功能的电流，而不是异构化：跳跃与不同比例的IBMX浓度稳定的光强度产生相等的电流，并遵循相同的适应过程中保持光，尽管10倍的照明差异。从IBMX诱导的电流与光诱导的电流之间的延迟来判断，信号通路上PDE之后是主要的反馈调节位点，暗激活PDE影响cGMP的水解通量和胞质扩散，以及cGMP活性信号对光响应的比例范围。
We studied the activation of 3',5'-cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE) by using a cell-permeant enzyme inhibitor. Rods of Ambystoma tigrinum held in a suction electrode were jumped into a stream of 3-isobutyl-1-methylxanthine (IBMX), 0.01-1 mM. Initial transient light-sensitive currents fit the notion that dark and light-activated forms of PDE contributed independently to metabolic activity and were equivalently inhibited by IBMX (apparent Ki 30 microns). Inhibition developed within 50 ms, producing a step decrease of enzyme velocity, which could be offset by activation with flashes or steps of light. The dark PDE activity was equivalent to light activation of enzyme by 1,000 isomerization rod-1s-1, sufficient to hydrolyze the free cGMP pool (1/e) in 0.6 s. Steady light activated PDE in linear proportion to isomerization rate, the range from darkness to current saturation amounting to a 10-fold increase. The conditions for simultaneous onset of inhibitor and illumination to produce no net change of membrane current defined the apparent lifetime of light- activated PDE, TPDE* = 0.9 s, which was independent of both background illumination and current over the range 0-3 x 10(5) isomerization s-1, from 50 to 0 pA. Adaptation was a function of current rather than isomerization: jumps with different proportions of IBMX concentration to steady light intensity produced equal currents, and followed the same course of adaptation in maintained light, despite a 10-fold difference of illumination. Judged from the delay between IBMX- and light-induced currents, the dominant feedback regulatory site comes after PDE on the signal path. The dark active PDE affects the hydrolytic flux and cytoplasmic diffusion of cGMP, as well as the proportional range of the cGMP activity signal in response to light.
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影响因子：
5.5
作者：
FORTI, S;MENINI, A;TORRE, V
通讯作者：
TORRE, V
影响因子：
3.5
作者：
FILATOV, GN;JAINAZAROV, AB;FESENKO, EE
通讯作者：
FESENKO, EE
DOI：
10.1098/rspb.1923.0006
发表时间：
1923-02-01
期刊：
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-CONTAINING PAPERS OF A BIOLOGICAL CHARACTER
影响因子：
--
作者：
Brown, WEL;Hill, AV
通讯作者：
Hill, AV
影响因子：
2.9
作者：
FLEISCHMAN, D;DENISEVICH, M
通讯作者：
DENISEVICH, M
影响因子：
2.9
作者：
FURMAN, RE;TANAKA, JC
通讯作者：
TANAKA, JC