Regulation of cloned ATP-sensitive K channels by adenine nucleotides and sulfonylureas: interactions between SUR1 and positively charged domains on Kir6.2.
Regulation of cloned ATP-sensitive K channels by adenine nucleotides and sulfonylureas: interactions between SUR1 and positively charged domains on Kir6.2.
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DOI：
10.1085/jgp.118.4.391
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发表时间：
2001-10
期刊：
影响因子：
--
通讯作者：
Ribalet B
中科院分区：
文献类型：
--
作者：
John SA;Weiss JN;Ribalet B
由孔形成蛋白Kir6.x和磺酰脲类受体SURx组成的KATP通道以相互依赖的方式由腺嘌呤核苷酸、PIP 2和磺酰脲类调节。为了深入了解这些相互作用，我们研究了Kir6.2中带正电荷残基的突变对腺嘌呤核苷酸和磺酰脲格列本脲通道调节的影响，Kir6.2先前与PIP 2的反应有关。我们的数据显示Kir6.2“PIP 2不敏感”突变体R176 C和R177 C在ATP诱导的抑制后不被MgADP重新激活，并且对格列本脲也不敏感。这些结果表明，R176和R177是功能性偶联SUR 1所必需的，SUR 1赋予MgADP和磺酰脲类药物对KATP通道的敏感性。与此相反，R301 C和R314 C突变体，这也是“PIP 2不敏感的”，仍然敏感的刺激MgADP在ATP的情况下，并抑制格列本脲。基于这些发现，以及以前的数据，我们提出了一个模型的KATP通道，其中在ATP的存在下，R176和R177残基的Kir6.2形成一个特定的网站，与NBF 1结合到ATP的SUR 1，促进通道开放，通过抵消ATP的抑制。这种相互作用通过MgADP与NBF 2的结合而促进，并通过磺酰脲类与SUR 1的结合而阻断。在缺乏ATP的情况下，由于KATP通道不被ATP阻断，因此它们不需要与R176和R177相互作用的NBF 1的抵消作用来打开。尽管如此，在这种状态下的通道仍然被MgADP激活。这种效应可以通过NBF 2/MgADP部分与Kir6.2的另一个区域（可能是NH 2末端）的直接刺激相互作用来解释，或者通过NBF 2/MgADP在不存在ATP的情况下仍然促进NBF 1和Kir6.2之间的弱相互作用来解释。由R301和R314界定的区域不参与与NBF 1或NBF 2的相互作用，但赋予额外的PIP 2敏感性。
KATP channels, comprised of the pore-forming protein Kir6.x and the sulfonylurea receptor SURx, are regulated in an interdependent manner by adenine nucleotides, PIP2, and sulfonylureas. To gain insight into these interactions, we investigated the effects of mutating positively charged residues in Kir6.2, previously implicated in the response to PIP2, on channel regulation by adenine nucleotides and the sulfonylurea glyburide. Our data show that the Kir6.2 “PIP2-insensitive” mutants R176C and R177C are not reactivated by MgADP after ATP-induced inhibition and are also insensitive to glyburide. These results suggest that R176 and R177 are required for functional coupling to SUR1, which confers MgADP and sulfonylurea sensitivity to the KATP channel. In contrast, the R301C and R314C mutants, which are also “PIP2-insensitive,” remained sensitive to stimulation by MgADP in the absence of ATP and were inhibited by glyburide. Based on these findings, as well as previous data, we propose a model of the KATP channel whereby in the presence of ATP, the R176 and R177 residues on Kir6.2 form a specific site that interacts with NBF1 bound to ATP on SUR1, promoting channel opening by counteracting the inhibition by ATP. This interaction is facilitated by binding of MgADP to NBF2 and blocked by binding of sulfonylureas to SUR1. In the absence of ATP, since KATP channels are not blocked by ATP, they do not require the counteracting effect of NBF1 interacting with R176 and R177 to open. Nevertheless, channels in this state remain activated by MgADP. This effect may be explained by a direct stimulatory interaction of NBF2/MgADP moiety with another region of Kir6.2 (perhaps the NH2 terminus), or by NBF2/MgADP still promoting a weak interaction between NBF1 and Kir6.2 in the absence of ATP. The region delimited by R301 and R314 is not involved in the interaction with NBF1 or NBF2, but confers additional PIP2 sensitivity.
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影响因子：
4.8
作者：
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通讯作者：
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影响因子：
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DOI：
10.1073/pnas.95.23.13953
发表时间：
1998-11-10
影响因子：
11.1
作者：
Drain, P;Li, LH;Wang, J
通讯作者：
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