P2X(1) receptor subunit contribution to gating revealed by a dominant negative PKC mutant.
The family of ATP-gated P2X receptor channels have a conserved protein kinase C site in the N-terminal intracellular domain. This site was disrupted in human P2X(1) receptors by the mutation T18A. T18A mutants were expressed at normal levels in Xenopus oocytes; however, the peak current amplitude was reduced by >99% and showed approximately 10 fold faster desensitisation in response to ATP than wild type (WT) receptors showed. P2X receptor subunits form functional trimeric channels. Co-expression of T18A and WT receptors (90:10 ratio) produced heteromeric T18A/WT channels with the rapid T18A time-course and an approximately 90-fold increase in peak current amplitude compared to T18A. Similarly, T18A dominated the desensitisation phenotype of heteromeric channels composed of T18A and slowly desensitising K68A mutants. These results suggest that phosphorylation of P2X(1) receptors has a dramatic effect on the time-course of the response and may provide a mechanism for regulating channel function.
Ennion
Steven J
SJ
Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, LE1 9HN, United Kingdom.
Evans
Richard J
RJ
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D016384:Consensus Sequence; D004553:Electric Conductivity; D015640:Ion Channel Gating; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011493:Protein Kinase C / Q000502:physiology*; D021122:Protein Subunits; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D016415:Sequence Alignment; D014982:Xenopus laevis
D021122:Protein Subunits; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D000255:Adenosine Triphosphate; D011493:Protein Kinase C