title: Neurofilament phosphorylation in cultured bovine adrenal chromaffin cells is stimulated by phorbol ester.
abstract: Primary cultures of bovine adrenal chromaffin cells contain neurofilament proteins that are hypophosphorylated. When the cells were grown in medium containing 32Pi and 0.1 microM 12-O-tetradecanoyl-phorbol 13-acetate (TPA), 32P-labelling of the three neurofilament subunits was increased 6- to 20-fold relative to controls, the highest level of stimulation occurring for the mid-sized subunit. Addition of the protease inhibitor leupeptin to the growth medium had no effect on TPA-stimulated phosphorylation. The increased 32P incorporation was accompanied by a marked reduction in the gel electrophoretic mobilities of the two largest subunits. The augmented phosphorylation was observed 10 min after addition of TPA to a concentration of 0.1 microM or after 1 h of incubation in the presence of 0.01 microM TPA. One-dimensional peptide mapping and phosphoamino acid analysis indicated that TPA stimulated the phosphorylation of seryl residues at new sites in the mid-sized subunit. All of the latter subunit contained in the cytoskeletal fraction of chromaffin cells was converted to a more highly phosphorylated state after the cells were grown in the presence of TPA for 1 h.
authors.affiliation: Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Georges
authors.forename: M H
authors.initials: MH
authors.lastname: Lindenbaum
authors.forename: M G
authors.initials: MG
authors.lastname: Sacher
authors.forename: J M
authors.initials: JM
authors.lastname: Trifaró
authors.forename: W E
authors.initials: WE
authors.lastname: Mushynski
mesh_terms: D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002838:Chromaffin System / Q000166:cytology / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D007382:Intermediate Filaments / Q000378:metabolism*; D010766:Phosphorylation; D013268:Stimulation, Chemical; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D013755:Tetradecanoylphorbol Acetate