Identification of RGS4 structures involved in its plasma membrane localization

• Published in: The FASEB journal Vol. 24; no. S1; p. lb103
• Main Authors: Bastin, Guillaume, Lachhar, Karanjit, Seong, Alex, Heximer, Scott
• Format: Journal Article
• Language: English
• Published: Federation of American Societies for Experimental Biology 01-04-2010
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.24.1_supplement.lb103

RGS4 is highly expressed in the sinoatrial node of the heart and plays an important role in the regulation of M2R‐mediated heart rate control. In order understand the intracellular mechanisms that may regulate RGS4 function in the heart and other tissues we set out to identify the key determinants of RGS4 function in cell culture models. Previous studies have shown that optimal function of R4 group proteins requires their efficient plasma membrane targeting. Based on their high degree of similarity, we set out to compare the localization and function of RGS4 and RGS5 in mammalian cells. Confocal microscopy shows that RGS4‐YFP is mainly localized to the plasma membrane of HEK cells whereas RGS5‐YFP, as reported previously, is found primarily in the cytosol. Comparison of the sequence differences between RGS4 and RGS4 has identified several regions in RGS4 that may promote its increased localization to the plasma membrane. Chimeric YFP‐tagged cDNA constructs for RGS4:RGS5 and RGS5:RGS4 indicate that critical residues in the carboxyl‐terminal domain of RGS4 (including the RGS box) may promote its specific targeting to the plasma membrane but that G‐protein binding is not required for this function. Current studies are aimed at defining the specific residues within the carboxyl terminal that promote its increased localization and function. This study was funded by the Heart and Stroke Foundation of Ontario Grant‐in‐Aid Program grants T6799