The neuronal Ca2+-binding protein 2 (NECAB2) interacts with the adenosine A2A receptor and modulates the cell surface expression and function of the receptor

Heptaspanning membrane also known as G protein-coupled receptors (GPCR) do interact with a variety of intracellular proteins whose function is regulate receptor traffic and/or signaling. Using a yeast two-hybrid screen, NECAB2, a neuronal calcium binding protein, was identified as a binding partner for the adenosine A2A receptor (A2AR) interacting with its C-terminal domain. Co-localization, co-immunoprecipitation and pull-down experiments showed a close and specific interaction between A2AR and NECAB2 in both transfected HEK-293 cells and also in rat striatum. Immunoelectron microscopy detection of NECAB2 and A2AR in the rat striatopallidal structures indicated that both proteins are co-distributed in the same glutamatergic nerve terminals. The interaction of NECAB2 with A2AR modulated the cell surface expression, the ligand-dependent internalization and the receptor-mediated activation of the MAPK pathway. Overall, these results show that A2AR interacts with NECAB2 in striatal neurones co-expressing the two proteins and that the interaction is relevant for A2AR function.