title: Coupling of RYR1 and L-type calcium channels via calmodulin binding domains.
abstract: In skeletal muscle the L-type Ca2+ channel directly controls the opening of the sarcoplasmic reticulum Ca2+ release channel (RYR1), and RYR1, in turn, prevents L-type Ca2+ channel inactivation. We demonstrate that the two proteins interact using calmodulin binding regions of both proteins. A recombinant protein representing amino acids 1393-1527 (D1393-1527) of the carboxyl-terminal tail of the skeletal muscle L-type voltage-dependent calcium channel binds Ca2+, Ca2+ calmodulin, and apocalmodulin. In the absence of calmodulin, D1393-1527 binds to both RYR1 and a peptide representing the calmodulin binding site of RYR1 (amino acids 3609-3643). In addition, biotinylated R3609-3643 peptide can be used with streptavidin beads to pull down [3H]PN200-110-labeled L-type channels from detergent-solubilized transverse tubule membranes. The binding of the L-type channel carboxyl-terminal tail to the calmodulin binding site on RYR1 may stabilize the contact between the two proteins, provide a mechanism for Ca2+ and/or calmodulin regulation of their interaction, or participate directly in functional signaling between these two proteins. A unique aspect of this study is the finding that calmodulin binding sequences can serve as specific binding motifs for proteins other than calmodulin.
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: S
authors.initials: S
authors.lastname: Sencer
authors.forename: R V
authors.initials: RV
authors.lastname: Papineni
authors.forename: D B
authors.initials: DB
authors.lastname: Halling
authors.forename: P
authors.initials: P
authors.lastname: Pate
authors.forename: J
authors.initials: J
authors.lastname: Krol
authors.forename: J Z
authors.initials: JZ
authors.lastname: Zhang
authors.forename: S L
authors.initials: SL
authors.lastname: Hamilton
mesh_terms: D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D011485:Protein Binding; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D020746:Calcium Channels, L-Type; D002147:Calmodulin; D019837:Ryanodine Receptor Calcium Release Channel