Conserved Gating Elements in TRPC4 and TRPC5 Channels
Conserved Gating Elements in TRPC4 and TRPC5 Channels
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DOI：
10.1074/jbc.m113.478305
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发表时间：
2013-07-05
影响因子：
4.8
通讯作者：
Flockerzi, Veit
中科院分区：
文献类型：
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作者：
Beck, Andreas;Speicher, Tilman;Flockerzi, Veit
TRPC 4和TRPC 5蛋白共享65%的氨基酸序列同一性，并形成Ca 2+渗透性非选择性阳离子通道。它们通过刺激与磷酸肌醇信号级联反应偶联的受体而激活。用丝氨酸残基取代两种蛋白质的胞质S4-S5接头内的保守甘氨酸残基迫使通道进入开放构象。TRPC 4（G503 S）和TRPC 5（G504 S）突变体的表达导致细胞死亡，这可以通过缓冲培养基的Ca 2+来防止。TRPC 4G（503 S）和TRPC 5（G504 S）突变离子通道的电流-电压关系分别类似于完全激活的TRPC 4和TRPC 5野生型通道的电流-电压关系.对TRPC 4的跨膜结构域和孔区域（S4-S6）的结构进行建模，预测在预测的S6螺旋的C-末端序列内的保守丝氨酸残基作为潜在的相互作用位点。将第二个突变（S623 A）引入TRPC 4（G503 S）抑制了组成性激活并部分挽救了其功能。这些结果表明，S4-S5接头是TRPC 4/C5通道门控的关键组成部分，并且其序列的干扰允许通道开放独立于任何传感器结构域。
TRPC4 and TRPC5 proteins share 65% amino acid sequence identity and form Ca2+ -permeable nonselective cation channels. They are activated by stimulation of receptors coupled to the phosphoinositide signaling cascade. Replacing a conserved glycine residue within the cytosolic S4-S5 linker of both proteins by a serine residue forces the channels into an open conformation. Expression of the TRPC4(G503S) and TRPC5(G504S) mutants causes cell death, which could be prevented by buffering the Ca2+ of the culture medium. Current- voltage relationships of the TRPC4G(503S) and TRPC5(G504S) mutant ion channels resemble that of fully activated TRPC4 and TRPC5 wild- type channels, respectively. Modeling the structure of the transmembrane domains and the pore region (S4-S6) of TRPC4 predicts a conserved serine residue within the C- terminal sequence of the predicted S6 helix as a potential interaction site. Introduction of a second mutation (S623A) into TRPC4(G503S) suppressed the constitutive activation and partially rescued its function. These results indicate that the S4-S5 linker is a critical constituent of TRPC4/C5 channel gating and that disturbance of its sequence allows channel opening independent of any sensor domain.