ABSTRACT
OBJECTIVE@#To investigate the effect of calmodulin (CaM) and its mutants on binding to voltage-gated Na channel isoleucine-glutamine domain (Na1.2 IQ).@*METHODS@#The cDNA of Na1.2 IQ was constructed by PCR technique, CaM mutants CaM, CaM and CaM were constructed with Quickchange site-directed mutagenesis kit (QIAGEN). The binding of Na1.2 IQ to CaM and CaM mutants under calcium and calcium free conditions were detected by pull-down assay.@*RESULTS@#Na1.2 IQ and CaM were bound to each other at different calcium concentrations, while GST alone did not bind to CaM. The binding affinity of CaM and Na1.2 IQ at [Ca]-free was greater than that at 100 nmol/L [Ca] ( < 0.05). In the absence of calcium, the binding amount of CaM wild-type to Na1.2 IQ was greater than that of its mutant, and the binding affinity of CaM to Na1.2 IQ was the weakest among the three mutants ( < 0.05).@*CONCLUSIONS@#The binding ability of CaM and CaM mutants to Na1.2 IQ is Ca-dependent. This study has revealed a new mechanism of Na1.2 regulated by CaM, which would be useful for the study of ion channel related diseases.