Mechanism of Zinc Potentiation of P2X Receptors

描述（由申请人提供）：P2X受体是由细胞外ATP门控的阳离子通道。这些通道的信号缺陷导致痛觉、男性生育能力和声音转导的缺陷。由P2X2亚基组成的同质通道在细胞外加锌时表现出atp诱导电流的增强。在P2X2中，额外的细胞组氨酸120和213是锌增强所独立需要的。假设这些残基直接参与锌结合位点，当锌结合时，这两个残基之间的距离发生变化，从而使离子通道的开放状态稳定。为了验证这一假设，将寻找其他可能参与结合锌的残基。此外，残基120和213将被一个小分子的结合阻断，并测量锌的增强量。根据这一假设，预计锌的增强作用会减弱。最后，残基120和213将与各种分子交联。预计一定尺寸的刚性交联剂将产生永久处于增强或非增强状态的通道，而不考虑锌的存在。

DESCRIPTION (provided by applicant): P2X receptors are cation channels gated by extra cellular ATP. Defects in signaling by these channels result in deficits in pain perception, male fertility, and sound transduction. Homomeric channels made up of the P2X2 subunit show potentiation of ATP-induced current when extra cellular zinc is applied. In P2X2, extra cellular histidines 120 and 213 are independently required for zinc potentiation. It is hypothesized that these residues directly participate in a zinc binding site, and that when zinc is bound, the distance between these two residues changes such that the open state of the ion channel is stabilized. To test this hypothesis, a search will be made for other residues potentially involved in binding zinc. Additionally, residues 120 and 213 will be blocked by the binding of a small molecule, and the amount of zinc potentiation will be measured. Based on the hypothesis, it is expected that zinc potentiation will decrease. Finally, residues 120 and 213 will be cross-linked with various molecules. It is expected that rigid cross linkers of certain size will yield channels that are permanently either in the potentiated or non-potentiated state, regardless of the presence of zinc.