Interactions of calmodulin with the multiple binding sites of cav1.2 Ca2+ channels

Although calmodulin binding to various sites of the cav1.2 ca2+ channel has been reported,the mechanism of the interaction is not fully understood. in this study we examined calmodulin binding to fragment channel peptides using a semi-quantitative pull-down assay. calmodulin bound to the peptides with decreasing affinity order: iq > preiq > i-ii loop > n-terminal peptide. a peptide containing both preiq and iq regions (leu1599 - leu1668) bound with approximately 2 mol of calmodulin per peptide. these results support the hypothesis that two molecules of calmodulin can simultaneously bind to the c-terminus of the cav1.2 channel and modulate its facilitatory and inhibitory activities. ©2010 the japanese pharmacological society.