The Dynamic Interaction Between Chemoattractant Receptor cAR1 And Coupled Heterotrimeric G-Protein

Abstract

G-protein coupled receptors, a widely studied class of membrane receptors, are often found upstream in intracellular signaling cascades. One such receptor, the cyclic adenosine monophosphate (cAMP) receptor cAR1 in the social amoeba Dictyostelium discoideum, is part of a cell’s chemotactic response. The cAR1 receptor binds cAMP and interacts with the heterotrimeric G-protein to initiate a signal cascade, resulting in cell movement. Our research focuses on understanding the interaction dynamics between cAR1 and the G-protein subunits. We studied the receptor in its wild type (WT) form, with several mutations (cAR1234), and truncated beyond residue 289 (cART289). Fluorescently tagged forms of cAR1 and G-protein subunits were synthesized and transfected into D. discoideum cell lines. Expression of the transfected cells was measured through developmental assays, Western blots, and BRET2 analysis. There is a diminished ability of cells with cAR1234 constructs to aggregate when compared to cells with the WTcAR. Cells containing the cART289 elicit some G-protein dissociation. These data suggest the interaction dynamics between cAR1 and the G-protein are affected by the regions mutated in cAR1234 and cART289. However, no substantial conclusions can be drawn yet regarding which region of the receptor is interacting with a particular G-protein subunit.