Module 3: Figure CaV1.2 L-type channel



Molecular organization of the CaV1.2 L-type channel from heart muscle.

The essential features of the channel are similar to those described for the CaV1.1 L-type channel from skeletal muscle (Module 3: Figure CaV1.1 L-type channel). A major difference concerns the modulatory mechanisms. The channel is modulated by protein kinase A (PKA) associated with A-kinase-anchoring protein of 18 kDa (AKAP18), which phosphorylates sites on both the α1C and β subunits. Protein kinase C (PKC) phosphorylates a site in the N-terminal region of the α1C subunit. The Ca2+-dependent inactivation of the channel is mediated by a resident calmodulin (CaM) bound to the C-terminal region. The red circle indicates the position of Gly-406 that is replaced by arginine in Timothy syndrome.