Referenced in: none

Automatically associated channels: Cav1.2

Title: Both N- and C-lobes of calmodulin are required for Ca2+-dependent regulations of CaV1.2 Ca2+ channels.

Authors: Feng Guo, Etsuko Minobe, Kazuto Yazawa, Hadhimulya Asmara, Xiao-yan Bai, Dong-yun Han, Li-Ying Hao, Masaki Kameyama

Journal, date & volume: Biochem. Biophys. Res. Commun., 2010 Jan 8 , 391, 1170-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20006578

Abstract
We investigated the concentration- and Ca(2+)-dependent effects of CaM mutants, CaM(12) and CaM(34), in which Ca(2+)-binding to its N- and C-lobes was eliminated, respectively, on the Ca(V)1.2 Ca(2+) channel by inside-out patch clamp in guinea-pig cardiomyocytes. Both CaM(12) and CaM(34) (0.7-10muM) applied with 3mM ATP produced channel activity after "rundown". Concentration-response curves were bell-shaped, similar to that for wild-type CaM. However, there was no obvious leftward shift of the curves by increasing [Ca(2+)], suggesting that both functional lobes of CaM were necessary for the Ca(2+)-dependent shift. However, channel activity induced by the CaM mutants showed Ca(2+)-dependent decrease, implying a Ca(2+) sensor existing besides CaM. These results suggest that both N- and C-lobes of CaM are required for the Ca(2+)-dependent regulations of Ca(V)1.2 Ca(2+) channels.