Chemical shift assignments of a calmodulin intermediate with two Ca 2+ bound in complex with the IQ-motif of voltage-gated Ca 2+ channels (Ca V 1.2).

Calcium-dependent inactivation (CDI) of neuronal voltage-gated Ca ²⁺ channels (Ca _V 1.2) is important for synaptic plasticity, which is associated with learning and memory. The Ca ²⁺ -dependent binding of calmodulin (CaM) to Ca _V 1.2 is essential for CDI. Here we report NMR assignments for a CaM mutant (D21A/D23A/D25A/E32Q/D57A/D59A/N61A/E68Q, called CaM ^EF12 ) that contains two Ca ²⁺ bound at the third and fourth EF-hands (EF3 and EF4) and is bound to the IQ-motif (residues 1644-1665) from Ca _V 1.2 (BMRB accession no. 27692).