Subunit structure and localization of dihydropyridine-sensitive calcium channels in mammalian brain, spinal cord, and retina.
Monoclonal antibodies that recognize the alpha 2 delta subunits of calcium channels from skeletal muscle immunoprecipitate a complex of alpha 1, alpha 2 delta, beta, and gamma subunits. They also immunoprecipitate 64% of rabbit brain dihydropyridine-sensitive calcium channels. Iodination of partially purified brain calcium channels followed by immunoprecipitation reveals alpha 1-, alpha 2 delta-, and beta-like subunits that have apparent molecular masses of 175, 142, and 57 kd, respectively. A polypeptide of 100 kd is also specifically immunoprecipitated. Immunocytochemical studies identify dihydropyridine-sensitive calcium channels in neuronal somata and proximal dendrites in rat brain, spinal cord, and retina. Staining of many neuronal somata is uneven, revealing relatively high densities of dihydropyridine-sensitive calcium channels at the base of major dendrites. L-type calcium channels in this location may serve to mediate long-lasting increases in intracellular calcium in the cell body in response to excitatory inputs to the dendrites.
Ahlijanian
M K
MK
Department of Pharmacology, School of Medicine, University of Washington, Seattle 98195.
Westenbroek
R E
RE
Catterall
W A
WA
D000818:Animals; D000911:Antibodies, Monoclonal; D001921:Brain / Q000166:cytology*; D015220:Calcium Channels / Q000187:drug effects / Q000648:ultrastructure*; D004095:Dihydropyridines / Q000494:pharmacology*; D005260:Female; D005455:Fluorescent Antibody Technique; D007124:Immunoenzyme Techniques; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000032:analysis* / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D009132:Muscles / Q000502:physiology; D009474:Neurons / Q000166:cytology; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000166:cytology*; D013116:Spinal Cord / Q000166:cytology*
D000911:Antibodies, Monoclonal; D015220:Calcium Channels; D004095:Dihydropyridines; D046911:Macromolecular Substances; D008565:Membrane Proteins; C038806:1,4-dihydropyridine