Subcellular localization of a novel G protein XLGαolf

XLGαolf was identified as a transcriptional variant of the heterotrimeric G protein, Gαolf. Previous work showed that XLGαolf couples with adenosine A2a receptor and dopamine D1 receptor in vitro. However, physiological functions of XLGαolf remain to be elucidated. In this study, we performed indirect immunofluorescence confocal analyses to examine the subcellular localization of XLGαolf. With overexpression, surprisingly, many large endosomes resulted. We also observed that XLGαolf localizes at the Golgi apparatus. The N-terminal region of XLGαolf appears necessary for both endosome formation and the Golgi localization. The results indicate that XLGαolf and Gαolf play distinctly separate roles. Moreover, XLGαolf colocalized with Rab3A and Rab8A, as well as partially with Rab11A, but not with other endocytotic endosomes. We could confirm the interaction between XLGαolf and Rab3A/Rab8A by co-immunoprecipitation experiments. Our study provides important clues toward understanding physiological functions of XLGαolf.