Interaction of calmodulin (CaM) with the C-terminus (CT) of the L-type CaV1.2 channel is crucial for Ca2+-dependent inactivation (CDI). CaM also binds to the N-terminus (NT), and a CaM-formed "bridge" between CT and NT has been proposed to control CDI. We characterized the interaction of CaM with its NT-binding peptide. Binding is Ca2+-dependent with an affinity of 0.6 μM. Mutations in NT of CaV1.2 that abolished the binding of CaM only slightly weakened the CDI but also accelerated the VDI. CaM did not foster an interaction between the CaM-binding peptides of NT and CT. Thus, the role of CaM's interaction with the CaV1.2 NT remains to be determined.
- Calcium channel