title: The Cav1.2 N terminus contains a CaM kinase site that modulates channel trafficking and function.
abstract: The L-type voltage-gated calcium channel Cav1.2 and the calcium-activated CaM kinase cascade both regulate excitation transcription coupling in the brain. CaM kinase is known to associate with the C terminus of Cav1.2 in a region called the PreIQ-IQ domain, which also binds multiple calmodulin molecules. Here we identify and characterize a second CaMKII binding site in the N terminus of Cav1.2 that is formed by a stretch of four amino residues (cysteine-isoleucine-serine-isoleucine) and which regulates channel expression and function. By using live cell imaging of tsA-201 cells we show that GFP fusion constructs of the CaMKII binding region, termed N2B-II co-localize with mCherry-CaMKII. Mutating CISI to AAAA ablates binding to and colocalization with CaMKII. Cav1.2-AAAA channels show reduced cell surface expression in tsA-201 cells, but interestingly, display an increase in channel function that offsets the trafficking deficit. Altogether our data reveal that the proximal N terminus of Cav1.2 contains a CaMKII binding region which contributes to channel surface expression and function.
authors.affiliation: Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Simms
authors.forename: Ivana A
authors.initials: IA
authors.lastname: Souza
authors.forename: Renata
authors.initials: R
authors.lastname: Rehak
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Zamponi
mesh_terms: D000200:Action Potentials; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats
chemical_list: D020746:Calcium Channels, L-Type; C419385:L-type calcium channel alpha(1C); D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2