An anti-peptide antibody specific for the class A calcium channel alpha 1 subunit labels mammalian neuromuscular junction.

We have generated an anti-peptide antibody specific for the class A calcium channel alpha 1 subunit from rat brain. In immunoblots of the calcium channel complex partially purified from rat brain membranes, the antibody specifically recognized two doublets, one of apparent M(r) 210,000 and M(r) 180,000 and another of apparent M(r) 160,000 and M(r) 130,000. Immunofluorescent staining of sections of rat diaphragm showed that this antibody specifically recognizes antigens that are highly concentrated at neuromuscular synapses. Using this antibody, we also examined the distribution of the class A alpha 1 subunit in sagittal sections of rat cerebellum by immunoperoxidase staining. Specific immunoreactivity was localized in the granule cell layer, possibly to the cerebellar glomeruli, the unique structures in cerebellum where mossy fibers synapse with granule cell dendrites. Purkinje cell neurons were not stained specifically. These results indicate that the class A calcium channel alpha 1 subunit is highly concentrated at mammalian neuromuscular junction and has a restricted localization in cerebellum that does not include Purkinje cell soma or dendrites.