G protein β subunits regulate Ca v 3.3 T-type channel activity and current kinetics via interaction with the Ca v 3.3 C-terminus

초록

Ca 2 + influx through Ca v 3.3 T -type channel plays crucial roles in neuronal excitability and is subject to regulation by various signaling molecules. However, our understanding of the partners of Ca v 3.3 and the related regulatory pathways remains largely limited. To address this quest, we employed the rat Ca v 3.3 C -terminus as bait in yeasttwo-hybrid screenings of a cDNA library, identifying rat G beta 2 as an interaction partner. Subsequent assays revealed that the interaction of G beta 2 subunit was specific to the Ca v 3.3 C -terminus. Through systematic dissection of the C -terminus, we pinpointed a 22 amino acid sequence (amino acids 1789 - 1810) as the G beta 2 interaction site. Coexpression studies of rat Ca v 3.3 with various G beta gamma compositions were conducted in HEK-293 cells. Patch clamp recordings revealed that coexpression of G beta 2 gamma 2 reduced Ca v 3.3 current density and accelerated inactivation kinetics. Interestingly, the effects were not unique to G beta 2 gamma 2, but were mimicked by G beta 2 alone as well as other G beta gamma dimers, with similar potencies. Deletion of the G beta 2 interaction site abolished the effects of G beta 2 gamma 2 . Importantly, these G beta 2 effects were reproduced in human Ca v 3.3. Overall, our findings provide evidence that G beta ( gamma ) complexes inhibit Ca v 3.3 channel activity and accelerate the inactivation kinetics through the G beta interaction with the Ca v 3.3 C -terminus.

키워드