The P2Y receptor family represents a wide-ranging set of G-protein-coupled receptors that respond to purinergic ligands, and are involved in many physiological processes. From signalling assays in tsA201 cells, the Kennedy lab has previously proposed the formation of a constitutive heterodimer between co-expressed human P2Y1 and P2Y12 receptors; this could represent a target for the control of pain sensing neurones. Therefore, it was aimed in this project to characterise if the receptors physically interacted using co-immunoprecipitation, and also to investigate the endogenous expression of other potentially interacting hP2Y receptors in the tsA201 cell line. In this study, tsA201 cells were determined to express mRNA for hP2Y1, 2, 4, 6, 12, 14 receptors using reverse transcriptase PCR and confirmatory Sanger sequencing. Furthermore, the cells demonstrated Ca2+ responses to all of the natural hP2Y receptor agonists tested, the order of potency being ADP > ATP > UTP > UDP. When co-expressing hP2Y1 and hP2Y12 receptors oppositely tagged with a HA or fluorescent protein (FP), immunoprecipitating for the HA tag and blotting for the FP showed a visible high molecular weight protein complex of ~130 to >250 KDa for either combination of receptors. This implied that the FP tagged receptor had co-immunoprecipitated with the other HA tagged receptor as this protein was also visible when blotting for the HA tag, signifying the presence of both tagged receptors in the complex. These results were overall suggestive of functional hP2Y1, 2, 12 receptor expression in the tsA201 cell line, and possibly also hP2Y4, 6, 14 receptors. The high molecular weight protein complex detected could represent a constitutive hP2Y1-hP2Y12 receptor heterodimer as proposed. Whilst it was not possible to specifically either confirm or refute the physical formation of the heterodimer with the data acquired, it was potentially supportive, and furthermore suggested other future paths of investigation.
The Arabidopsis FLC protein interacts directlyin vivowithSOC1andFTchromatin and is part of a high-molecular-weight protein complex