Activation-dependent changes in receptor distribution and dendritic morphology in hippocampal neurons expressing P2X(2)-green fluorescent protein receptors

ATP-gated P2X(2) receptors are widely expressed in neurons, but the cellula r effects of receptor activation are unclear. We engineered functional gree n fluorescent protein (GFP)-tagged P2X(2) receptors and expressed them in e mbryonic hippocampal neurons, and report an approach to determining functio nal and total receptor pool sizes in living cells. ATP application to dendr ites caused receptor redistribution and the formation of varicose hot spots of higher P2X(2)-GFP receptor density. Redistribution in dendrites was acc ompanied by an activation-dependent enhancement of the ATP-evoked current. substate-specific mutant T18A P2X(2)-GFP receptors showed no redistribution or activation-dependent enhancement of the ATP-evoked current. Thus fluore scent P2X(2)-GFP receptors function normally, can be quantified, and reveal the dynamics of P2X(2) receptor distribution on the seconds time scale.