P400 protein characteristic to Purkinje cells and related proteins in cerebella from neuropathological mutant mice: autoradiographic study by 14C-leucine and phosphorylation.

P400 protein has been found in the cerebellum and localizes to Purkinje cells. It is a glycoprotein and reacts with plant lectins. Autoradiographic patterns of the protein profiles of mutant mice cerebella after intracranial injections of 14C-leucine were analyzed. P400 protein was one of the dominant proteins labeled in the control cerebellum. No incorporation of 14C-leucine to the position of P400 protein was found in the nervous and pcd mutant mice where no Purkinje cells and no P400 protein are present. P400 protein in weaver cerebellum was labelled more intensely than that in the control. In the staggerer mice, where dendritic arborization of Purkinje cell is poor and no spines are formed on the dendrites, no P400 protein was found and no 14C-leucine incorporation was observed to the position of P400 protein, suggesting that staggerer is a mutation where no P400 protein accumulated in the fractions being studied. P400 protein was phosphorylated independently of the presence of Ca2+. Among the proteins of the isolated Purkinje cells, P400 protein was one of the major proteins phosphorylated.