SUBUNIT STRUCTURE AND LOCALIZATION OF DIHYDROPYRIDINE-SENSITIVE CALCIUM CHANNELS IN MAMMALIAN BRAIN, SPINAL-CORD, AND RETINA

Monoclonal antibodies that recognize the α2δ subunits of calcium channels from skeletal muscle immunoprecipitate a complex of α1, α2δ, β, and γ subunits. They also immunoprecipitate 64% of rabbit brain dihydropyridine-sensitive calcium channels. Iodination of partially purified brain calcium channels followed by immunoprecipitation reveals α1-, α2δ-, and β-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. © 1990.