Protein kinase C phosphorylation of desmin at four serine residues within the non-alpha-helical head domain.
We reported that phosphorylation by either cAMP-dependent protein kinase or protein kinase C (Ca2+/phospholipid-dependent enzyme) in vitro induces disassembly of the desmin filaments (Inagaki, M., Gonda, Y., Matsuyama, M., Nishizawa, K., Nishi, Y., and Sato, C. (1988) J. Biol. Chem. 263, 5970-5978). For this subunit protein, Ser-29, Ser-35, and Ser-50 within the non-alpha-helical head domain were shown to be the sites of phosphorylation for cAMP-dependent protein kinase (Geisler, N., and Weber, K. (1988) EMBO J. 7, 15-20). In the present work, we identified the sites of desmin phosphorylated in vitro by other protein kinase which affects the filament structure. The protein kinase C-phosphorylated desmin was hydrolyzed with trypsin, and the phosphorylated peptides were isolated by reverse-phase chromatography. Sequential analysis of the purified phosphopeptides, together with the known primary sequence, revealed that Ser-12, Ser-29, Ser-38, and Ser-56 were phosphorylated by protein kinase C. All four sites are located within the non-alpha-helical head domain of desmin. Ser-12, Ser-38, and Ser-56, specifically phosphorylated by protein kinase C, have arginine residues at the carboxyl-terminal side (Arg-14, Arg-42, and Arg-59, respectively). Ser-29 phosphorylated by both protein kinase C and cAMP-dependent protein kinase has arginine residues at the amino and carboxyl termini (Arg-27 and Arg-33). These findings support the view that the head domain-specific phosphorylation strongly influences desmin filament structure; however, each protein kinase differed with regard to site recognition on this domain.
Kitamura
S
S
Laboratory of Experimental Radiology Aichi Cancer Center Research Institute, Japan.
Ando
S
S
Shibata
M
M
Tanabe
K
K
Sato
C
C
Inagaki
M
M
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001921:Brain / Q000201:enzymology; D003893:Desmin / Q000378:metabolism*; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011487:Protein Conformation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D012694:Serine; D013379:Substrate Specificity
D000596:Amino Acids; D003893:Desmin; D010748:Phosphopeptides; D012694:Serine; D011493:Protein Kinase C