Subunit structure and localization of dihydropyridine-sensitive calcium channels in mammalian brain, spinal cord, and retina |
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Authors: | M K Ahlijanian R E Westenbroek W A Catterall |
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Affiliation: | Department of Pharmacology, School of Medicine, University of Washington, Seattle 98195. |
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Abstract: | 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 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. |
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