Translation-independent association of mRNAs encoding protomers of the 5-HT2A-mGlu2 receptor complex in living cells

Abstract

SUMMARYThe serotonin 2A receptor (5-HT2AR) and the metabotropic glutamate 2 receptor (mGluR2) form heteromeric G protein-coupled receptor (GPCR) complexes through a direct physical interaction. Co-translational association of mRNAs encoding subunits of heteromeric ion channels has been reported, but whether complex assembly of GPCRs occurs during translation remains unknown. Ourin vitrodata reveal evidence of co-translational modulation in5-HT2ARandmGluR2mRNAs following siRNA-mediated knockdown. Interestingly, immunoprecipitation of either 5-HT2AR or mGluR2, using an antibody targeting epitope tags at their N-terminus, results in detection of both transcripts associated with ribonucleoprotein complexes containing RPS24. Additionally, we demonstrate that the mRNA transcripts of5-HT2ARandmGluR2associate autonomously of their respective encoded proteins. Validation of this translation-independent association is extendedex vivousing mouse frontal cortex samples. Together, these findings provide mechanistic insights into the co-translational assembly of GPCR heteromeric complexes, unraveling regulatory processes governing protein-protein interactions and complex formation.