Mechanism of inhibition of cyclic nucleotide-gated ion channels by diacylglycerol.
Mechanism of inhibition of cyclic nucleotide-gated ion channels by diacylglycerol.
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DOI：
10.1085/jgp.116.6.755
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发表时间：
2000-12
期刊：
影响因子：
--
通讯作者：
Zimmerman AL
中科院分区：
文献类型：
--
作者：
Crary JI;Dean DM;Nguitragool W;Kurshan PT;Zimmerman AL
环核苷酸门控(CNG)通道是视觉和嗅觉信号转导通路中的关键组成部分，它们主要是响应环核苷酸胞浆浓度的变化而门控的。我们先前发现，未发生磷酸化反应的二酰甘油类似物(Gordon，S.E.，J.Downing-Park，B.和A.L.Zimmerman)显著抑制cGMP开放天然杆状CNG通道的能力。1995年。生物群落。J.69：409-417)。在这里，我们研究了克隆的牛视杆和大鼠嗅觉CNG通道在非洲爪哇卵母细胞中的表达，并确定它们被DAG不同程度地抑制。饱和[cGMP]时，DAG对同质多聚体(仅α亚单位)通道的抑制作用与天然杆状CNG通道相似，但DAG对同质多聚体嗅觉通道的抑制作用较弱，即使在高浓度时也只产生部分抑制。然而，在低开放概率(Po)时，这两个通道对DAG更敏感，这表明DAG是一种闭合状态的抑制物。DAG抑制的Hill系数通常大于1，这表明有效抑制一个通道需要不止一个DAG分子。在单通道记录中，DAG降低了Po，但不降低单通道电导。杆状通道和嗅觉通道嵌合体的结果表明，DAG抑制的差异更多地与跨膜片段及其连接环的差异有关，而不是与氨基和羧基末端的差异有关。我们的结果与多个DAG分子通过直接与通道结合和/或改变双层-通道相互作用来稳定CNG通道的闭合状态(S)的模型是一致的。我们推测，如果DAG直接与通道相互作用，它可能插入到每个亚基跨膜区之间的疏水缝隙中，或者插入通道和双层之间的疏水界面。
Cyclic nucleotide–gated (CNG) channels are critical components in the visual and olfactory signal transduction pathways, and they primarily gate in response to changes in the cytoplasmic concentration of cyclic nucleotides. We previously found that the ability of the native rod CNG channel to be opened by cGMP was markedly inhibited by analogues of diacylglycerol (DAG) without a phosphorylation reaction (Gordon, S.E., J. Downing-Park, B. Tam, and A.L. Zimmerman. 1995. Biophys. J. 69:409–417). Here, we have studied cloned bovine rod and rat olfactory CNG channels expressed in Xenopus oocytes, and have determined that they are differentially inhibited by DAG. At saturating [cGMP], DAG inhibition of homomultimeric (α subunit only) rod channels was similar to that of the native rod CNG channel, but DAG was much less effective at inhibiting the homomultimeric olfactory channel, producing only partial inhibition even at high [DAG]. However, at low open probability (Po), both channels were more sensitive to DAG, suggesting that DAG is a closed state inhibitor. The Hill coefficients for DAG inhibition were often greater than one, suggesting that more than one DAG molecule is required for effective inhibition of a channel. In single-channel recordings, DAG decreased the Po but not the single-channel conductance. Results with chimeras of rod and olfactory channels suggest that the differences in DAG inhibition correlate more with differences in the transmembrane segments and their attached loops than with differences in the amino and carboxyl termini. Our results are consistent with a model in which multiple DAG molecules stabilize the closed state(s) of a CNG channel by binding directly to the channel and/or by altering bilayer–channel interactions. We speculate that if DAG interacts directly with the channel, it may insert into a putative hydrophobic crevice among the transmembrane domains of each subunit or at the hydrophobic interface between the channel and the bilayer.
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DOI：
10.1085/jgp.109.1.3
发表时间：
1997-01
期刊：
The Journal of general physiology
影响因子：
--
作者：
Fodor AA;Gordon SE;Zagotta WN
通讯作者：
Zagotta WN
影响因子：
64.8
作者：
Chyb, S;Raghu, P;Hardie, RC
通讯作者：
Hardie, RC
影响因子：
2.4
作者：
Balasubramanian, S;Lynch, JW;Barry, PH
通讯作者：
Barry, PH
影响因子：
3.8
作者：
KARPEN, JW;BROWN, RL;BAYLOR, DA
通讯作者：
BAYLOR, DA
影响因子：
3.5
作者：
BIEL, M;ALTENHOFEN, W;HOFMANN, F
通讯作者：
HOFMANN, F