Expression and electrophysiological function of actin in chick cerebellar neurons

Among several monoclonal antibodies obtained by immunizing Balb/c mice with cerebellar synaptic membrane fractions from E20 chick embryos, the antibod y, named M35, suppressed Ca-spikes in immature cultured chick cerebellar ne urons. M35 immunoprecipitated 43kDa protein from a I-125-labeled embryonic crude cerebellar membrane fraction. Immunohistochemically, the M35 antigen was expressed most intensively in Purkinje cells, but its expression was li mited to highly motile structures at developmental neuronal remodeling. Ele ctrophysiologically, M35 facilitated current responses to AMPA and inhibite d the responses to GABA in cultured cerebellar Purkinje neurons. The severa l peptides derived from the affinity-purified 43kDa protein were found to h ave homologous amino acid sequences to non-muscle actins. These results sug gest that the antigen recognized by M35 may play an essential role probably as membrane ion channels modulating synaptic functions in not only the dev elopment and growth but also the neuronal activity of chick cerebellar Purk inje cells.