title: Association of neuronal calcium channels with modular adaptor proteins.
abstract: Presynaptic voltage-gated calcium (Ca(2+)) channels mediate Ca(2+) influx into the presynaptic terminal that triggers synaptic vesicle fusion and neurotransmitter release. The immediate proximity of Ca(2+) channels to the synaptic vesicle release apparatus is critical for rapid and efficient synaptic transmission. In a series of biochemical experiments, we demonstrate a specific association of the cytosolic carboxyl terminus of the N-type Ca(2+) channel pore-forming alpha(1B) subunit with the modular adaptor proteins Mint1 and CASK. The carboxyl termini of alpha(1B) bind to the first PDZ domain of Mint1 (Mint1-1). The proline-rich region present in the carboxyl termini of alpha(1B) binds to the SH3 domain of CASK. Mint1-1 is specific for the E/D-X-W-C/S-COOH consensus, which defines a novel class of PDZ domains (class III). The Mint1-1 PDZ domain-binding motif is present only in the "long" carboxyl-terminal splice variants of N-type (alpha(1B)) and P/Q-type (alpha(1A)) Ca(2+) channels, but not in R-type (alpha(1E)) or L-type (alpha(1C)) Ca(2+) channels. Our results directly link presynaptic Ca(2+) channels to a macromolecular complex formed by modular adaptor proteins at synaptic junction and advance our understanding of coupling between cell adhesion and synaptic vesicle exocytosis.
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
authors.forename: A
authors.initials: A
authors.lastname: Maximov
authors.forename: T C
authors.initials: TC
authors.lastname: Südhof
authors.forename: I
authors.initials: I
authors.lastname: Bezprozvanny
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins / Q000378:metabolism*; D002448:Cell Adhesion; D005089:Exocytosis; D051528:Guanylate Kinases; D008024:Ligands; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D015398:Signal Transduction; D009435:Synaptic Transmission; D015003:Yeasts; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C513071:Apba1 protein, rat; D015220:Calcium Channels; D002352:Carrier Proteins; D008024:Ligands; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C106868:CASK kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; D002118:Calcium