Phosphorylation of 68 kDa neurofilament proteins has no significant effect on their assembly.

Native low molecular weight neurofilaments (NF-L) from bovine spinal cord with original phosphate content of 0.4 moles of phosphate per 1 mol of protein were phosphorylated with cyclic AMP dependent protein kinase and protein kinase C. In a similar way recombinant mouse NF-L proteins which did not contain any phosphate were phosphorylated with the same enzymes in both, the assembled and disassembled forms. The final phosphate content in both types of NF-L proteins reached about 4 moles of phosphate per 1 mol of protein. This phosphorylation had no effect on the assembly of NF-L into filaments as observed by electron microscopy.