Binding of 14-3-3β Regulates the Kinase Activity and Subcellular Localization of Testicular Protein Kinase 1

Junko Y. Toshima, Jiro Toshima, Takehiko Watanabe, Kensaku Mizuno
2001 Journal of Biological Chemistry  
Testicular protein kinase 1 (TESK1) is a serine/threonine kinase that phosphorylates cofilin and induces actin cytoskeletal reorganization. The kinase activity of TESK1 is stimulated by integrin-mediated signaling pathways, but the mechanism of regulation has remained unknown. By using the yeast two-hybrid system, we identified 14-3-3␤ to be the binding protein of TESK1. Specific interaction between TESK1 and 14-3-3␤ became evident in in vitro and in vivo co-precipitation assays. 14-3-3␤
more » ... ays. 14-3-3␤ interacts with TESK1 through the C-terminal region of TESK1 and in a manner dependent on the phosphorylation of Ser-439 within an RXXSXP motif. Binding of 14-3-3␤ inhibited the kinase activity of TESK1. During cell spreading on fibronectin, the TESK1/14-3-3␤ interaction significantly decreased, in a time course that inversely correlated with increase in TESK1 kinase activity. Thus, the dissociation of 14-3-3␤ from a TESK1/14-3-3␤ complex is likely to be involved in the integrin-mediated TESK1 activation. In HeLa cells, TESK1, together with 14-3-3␤, accumulated at the cell periphery when cells were plated on fibronectin, whereas they were diffusely distributed in the cytoplasm in the case of non-stimulated cells. We propose that 14-3-3␤ plays important roles in regulating the kinase activity of TESK1 and localizing TESK1 to cell adhesion sites following integrin stimulation.
doi:10.1074/jbc.m104620200 pmid:11555644 fatcat:rwgu5dqsdjd6doa4sdomkrolqi