Covalent modification of mutant rat P2X2 receptors with a thiol-reactive fluorophore allows channel activation by zinc or acidic pH without ATP.

ABSTRACT: Rat P2X2 receptors open at an undetectably low rate in the absence of ATP. Furthermore, two allosteric modulators, zinc and acidic pH, cannot by themselves open these channels. We describe here the properties of a mutant receptor, K69C, before and after treatment with the thiol-reactive fluorophore Alexa Fluor 546 C(5)-maleimide (AM546). Xenopus oocytes expressing unmodified K69C were not activated under basal conditions nor by 1,000 µM ATP. AM546 treatment caused a small increase in the inward holding current which persisted on washout and control experiments demonstrated this current was due to ATP independent opening of the channels. Following AM546 treatment, zinc (100 µM) or acidic external solution (pH 6.5) elicited inward currents when applied without any exogenous ATP. In the doubl

SUBMITTER: Dellal SS 

PROVIDER: S-EPMC3480388 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature