Metabotropic glutamate type 1α receptor localizes in low-density caveolin-rich plasma membrane fractions


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Recent evidence suggest that many G protein-coupled receptors (GPCR) and signalling molecules localize in microdomains of the plasma membrane. In this study, flotation gradient analysis in the absence of detergents demonstrated the presence of the metabotropic glutamate receptor type 1α (mGlu1α) in low-density caveolin-enriched membrane fractions (CEMF) in permanently transfected BHK cells. BHK-1α cells exhibit a similar pattern of staining for caveolin-1 and caveolin-2, and these two proteins show a high degree of co-localization with mGlu1α receptor as demonstrated by immunogold and confocal laser microscopy. The presence of mGlu1α in CEMF was also demonstrated by co-immunoprecipitation of mGlu1α receptor using antibodies against caveolin proteins. Activation of the mGlu1α receptor by agonist increased extracellular signal-regulated kinases phosphorylation in CEMF and not in high-density membrane fractions (HDMF), suggesting that mGlu1α receptor-mediated signal transduction could occur in caveolae-like domains. Overall, these results clearly show a molecular and functional association of mGlu1α receptor with caveolins.