Sequence differences in the IQ motifs of CaV1.1 and CaV1.2 strongly impact calmodulin binding and calcium-dependent inactivation.

ABSTRACT: The proximal C terminus of the cardiac L-type calcium channel (Ca(V)1.2) contains structural elements important for the binding of calmodulin (CaM) and calcium-dependent inactivation, and exhibits extensive sequence conservation with the corresponding region of the skeletal L-type channel (Ca(V)1.1). However, there are several Ca(V)1.1 residues that are both identical in six species and are non-conservatively changed from the corresponding Ca(V)1.2 residues, including three of the "IQ motif." To investigate the functional significance of these residue differences, we used native gel electrophoresis and expression in intact myotubes to compare the binding of CaM to extended regions (up to 300 residues) of the C termini of Ca(V)1.1 and Ca(V)1.2. We found that in the presence of Ca(2+) (eithe

SUBMITTER: Ohrtman J 

PROVIDER: S-EPMC2570861 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature