Referenced in: none

Automatically associated channels: Cav1.2

Title: Nucleotides maintain the activity of Cav1.2 channels in guinea-pig ventricular myocytes.

Authors: Shu-yuan Liu, Jian-Jun Xu, Etsuko Minobe, Qing-hua Gao, Rui Feng, Mei-mi Zhao, Feng Guo, Lei Yang, Li-Ying Hao, Masaki Kameyama

Journal, date & volume: Biochem. Biophys. Res. Commun., 2015 May 8 , 460, 813-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25824040

Abstract
The activity of Cav1.2 Ca(2+) channels is maintained in the presence of calmodulin and ATP, even in cell-free patches, and thus a channel ATP-binding site has been suggested. In this study, we examined whether other nucleotides, such as GTP, UTP, CTP, ADP and AMP, could be substituted for ATP in guinea-pig ventricular myocytes. We found that all the nucleotides tested could re-prime the Ca(2+) channels in the presence of 1 μM calmodulin in the inside-out mode. The order of efficacy was ATP > GTP > UTP > ADP > CTP ≈ AMP. Thus, the presumed nucleotide-binding site in the channel seemed to favor a purine rather than pyrimidine base and a triphosphate rather than a di- or mono-phosphate group. Furthermore, a high concentration (10 mM) of GTP, UTP, CTP, ADP and AMP had inhibitory effects on the channel activity. These results provide information on the putative nucleotide-binding site(s) in Cav1.2 Ca(2+) channels.