The regulation of intermediate filament reorganization in mitosis. p34cdc2 phosphorylates vimentin at a unique N-terminal site.
The disassembly of vimentin-containing intermediate filament (IF) networks during mitosis in BHK-21 cells is accompanied by increased phosphorylation of vimentin (Chou, Y.-H., Rosevear, E., and Goldman, R. D. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 1885-1889). We have recently identified p34cdc2 as the catalytic subunit of one of the two endogenous vimentin kinases in mitotic baby hamster kidney cells (Chou, Y.-H., Bischoff, J. R., Beach, D., and Goldman, R. D. (1990) Cell 62, 1063-1071). To begin to characterize the biochemical basis of the p34cdc2-mediated IF disassembly process, we have purified and sequenced the 32P-labeled tryptic peptides derived from in vitro-phosphorylated vimentin. The results demonstrate that Ser-55, in the N-terminal non-alpha-helical domain of vimentin, is the most favored phosphorylation site. This finding supports the idea that the N-terminal domain of type III IF protein plays a crucial role in regulating IF structure and supramolecular organization.
Chou
Y H
YH
Department of Cell, Molecular, and Structural Biology, Northwestern University, Chicago, Illinois 60611.
Ngai
K L
KL
Goldman
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001345:Autoradiography; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D007382:Intermediate Filaments / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010766:Phosphorylation; D014357:Trypsin; D014746:Vimentin / Q000378:metabolism*
D014746:Vimentin; D016203:CDC2 Protein Kinase; D014357:Trypsin