Autophosphorylation-dependent protein kinase phosphorylates Ser25, Ser38, Ser65, Ser71, and Ser411 in vimentin and thereby inhibits cytoskeletal intermediate filament assembly.
The autophosphorylation-dependent protein kinase has been identified as a potent vimentin kinase that incorporates 2 mol of phosphates per mol of protein and generates five major phosphorylation sites in vimentin. Tryptic phosphopeptide mapping by high-performance liquid chromatography followed by sequential manual Edman degradation and direct peptide sequence analysis revealed that Ser-25, Ser-38, Ser-65, and Ser-71 in the amino-terminal domain and Ser-411 in the carboxyl-terminal domain are the phosphorylation sites in vimentin phosphorylated by this kinase, indicating that autophosphorylation-dependent protein kinase is a potent and unique vimentin kinase. Functional study further revealed that phosphorylation of vimentin by autophosphorylation-dependent protein kinase can completely inhibit polymerization and assembly of the cytoskeletal intermediate filament as demonstrated by electron microscopic analysis. Taken together, the results provide initial evidence that the autophosphorylation-dependent protein kinase may function as a vimentin kinase involved in the structure-function regulation of the cytoskeletal system. The results also support the notion that this cyclic nucleotide- and calcium-independent protein kinase may function as a multisubstrate/multifunctional protein kinase involved in the regulation of diverse cell functions.
Institute of Biomedical and Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, ROC.
T J
TJ
Huang
T T
TT
Lee
W C
WC
Lee
Y K
YK
Lai
J S
JS
Yu
S D
SD
Yang
D000595:Amino Acid Sequence; D000818:Animals; D007382:Intermediate Filaments / Q000737:chemistry*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*; D012694:Serine / Q000378:metabolism; D013552:Swine; D014746:Vimentin / Q000378:metabolism*
D014746:Vimentin; D012694:Serine; D011494:Protein Kinases