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Analysis of a Bacterial Lipopolysaccharide‐Activated Serine Kinase That Phosphorylates p65/L‐Plastin in Macrophages
Author(s) -
Hagi Akifumi,
Hirata Hajime,
Shinomiya Hiroto
Publication year - 2006
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2006.tb03801.x
Subject(s) - phosphorylation , kinase , protein kinase a , serine , mitogen activated protein kinase kinase , biology , cyclin dependent kinase 9 , map kinase kinase kinase , map2k7 , mapk14 , biochemistry , cyclin dependent kinase 2 , microbiology and biotechnology
We previously identified p65/L‐plastin as a phosphorylated protein in LPS‐stimulated macrophages and determined its phosphorylation site. In vitro kinase assay using peptide substrates revealed that LPS‐stimulated kinase activity selectively phosphorylated their serine‐5 (Ser‐5) residue. Kinase inhibitors for cAMP‐dependent kinase such as H‐89 inhibited the Ser‐5 phosphorylation, but cAMP was not essential for the kinase activity. The LPS‐stimulated kinase activity in cytosol fractions of macrophages was recovered as a sharp peak by anion exchange chromatography. These findings suggest that an as yet unknown H‐89‐sensitive serine kinase is rapidly activated by LPS stimulation and then phosphorylates p65/L‐plastin, playing a vital role in macrophage activation.