Abstract
Modulation of G protein-coupled receptor (GPCR) signaling by local changes in intracellular calcium concentration is an established function of Calmodulin (CaM) which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca(2+)-sensor proteins that frequently associate with CaM targets with different functional outcome. In the present study we aimed to investigate if a target of CaM-the A(2A) adenosine receptor is able to associate with two other neuronal calcium binding proteins (nCaBPs), namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer (BRET) and co-immunoprecipitation experiments we show the existence of A(2A)-NCS-1 complexes in living cells whereas caldendrin did not associate with A(2A) receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A(2A) receptor intracellular signaling in a Ca(2+)-dependent manner. Taken together this study provides further evidence that neuronal Ca(2+)-sensor proteins play an important role in modulation of GPCR signaling.