Processing of neurofilament proteins from perikaryal to axonal type.

In previous studies, neuronal cell bodies, excised by hand from bovine spinal ganglia, were analyzed and heterogeneous intermediate and high molecular weight neurofilament proteins that differed in electrophoretic mobility from their axonal counterparts were demonstrated. In the present experiment, intermediate and high molecular weight neurofilament proteins of the axonal type were treated with alkaline phosphatase, and neurofilament proteins enriched in perikaryal type proteins were labeled with 32P. Results showed that neurofilament proteins were phosphorylated after their translation, in the perikarya and the proximal portion of the axon, and suggested that phosphorylation was responsible for the differences between axonal and perikaryal neurofilament proteins.