CaMKII phosphorylates a threonine residue in the C-terminal tail of Cav1.2 Ca2+ channel and modulates the interaction of the channel with calmodulin

• DOI: 10.1007/s12576-009-0033-y
• Publication Date: 2009-04-07T17:54:22Z
• Authors: Wu-Yang Wang; Li-Ying Hao; Etsuko Minobe; Zahangir Alam Saud; Dong-Yun Han; Masaki Kameyama
• Keywords: Threonine; 0301 basic medicine; Patch-Clamp Techniques; Calcium Channels, L-Type; Guinea Pigs; In Vitro Techniques; Peptide Fragments; Recombinant Proteins; Rats; Kinetics; 03 medical and health sciences; Amino Acid Substitution; Calmodulin; Mutagenesis, Site-Directed; Animals; Humans; Rabbits; Phosphorylation; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Protein Binding

We have previously found that both CaMKII-mediated phosphorylation and calmodulin (CaM) binding to the channels are required for maintaining basal activity of the Cav1.2 Ca(2+) channels. In this study, we investigated the hypothetical CaMKII phosphorylation site on Cav1.2 that contributes to the channel regulation. We found that CaMKII phosphorylates the Thr1603 residue (Thr1604 in rabbit) within the preIQ region in the C-terminal tail of the guinea-pig Cav1.2 channel. Mutation of Thr1603 to Asp (T1603D) slowed the run-down of the channel in inside-out patch mode and abolished the time-dependency of the CaM's effects to reverse run-down. We also found that CaMKII-mediated phosphorylation of the proximal C-terminal fragment (CT1) increased, while dephosphorylation of CT1 decreased its binding with CaM. These findings suggest that CaMKII regulates the CaM binding to the channel, and thereby maintains basal activity of the Cav1.2 Ca(2+) channel.