Editors' ChoiceKinase Regulation

FIP200 Nixes Pyk2 Activity

Science's STKE  25 Apr 2000:
Vol. 2000, Issue 29, pp. tw1
DOI: 10.1126/stke.2000.29.tw1

Proline-rich tyrosine kinase 2 (Pyk2) is activated by several extracellular stimuli, and Pyk2 activation appears to correlate with increased levels of calcium in cells. Ueda et al. identify FIP200, a protein that binds to Pyk2 and the focal adhesion kinase (FAK). FIP200 localized to the cytoplasm with Pyk2, and not to focal contacts where FAK is located. The COOH-terminal region of FIP200 associated with the Pyk2 kinase domain, and subsequent in vitro and in vivo kinase assays revealed that FIP200 inhibits the kinase activity of Pyk2. Coprecipitation experiments demonstrated that activation of Pyk2 correlates with dissociation of FIP200 from Pyk2. Coexpression of Pyk2 and FIP200 in Rat-1 cells blocked Pyk2-dependent apoptosis, whereas expression of FIP200 alone did not reduce basal apoptosis in Rat-1 cells. Thus, the role of FIP200 may be to prevent aberrant activation of Pyk2 in the absence of appropriate stimuli.

Ueda, H., Abbi, S., Zheng, C., and Guan, J.-L. (2000) Suppression of Pyk2 kinase and cellular activities by FIP200. J. Cell Biol. 149: 423-430. [Abstract] [Full Text]