Vimentin, a cytoskeletal substrate of protein kinase C

Evidence is shown that vimentin, the intermediate filament protein, is a substrate for protein kinase C: (a) Purified vimentin from Chinese hamster ovary cells can be phosphorylated by protein kinase C prepared from rabbit peritoneal neutrophils. Tryptic peptic analysis reveals multiple sites of phosphorylation distinct from those phosphorylated by cAMP-dependent protein kinase. (b) phosphorylation of membrane associated vimentin is stimulated in phorbol 12-myristate 13-acetate treated neutrophil membranes, suggesting that vimentin can be a substrate for membrane associated protein kinase C and (c) phorbol 12-myristate 13-acetate also stimulates the phosphorylation of vimentin in 32P-labeled intact neutrophils.