Anti-TNK1: Mouse TNK1 Antibody

Tnk1/Kos1 is implicated in negative regulation of cell growth by a mechanism involving inhibition of Ras activation and requiring Tnk1/Kos1’s intrinsic catalytic activity. Tnk1/Kos1 null mice were created by homologous recombination by deleting the catalytic domain. Upon aging, both Tnk1+/− and Tnk1−/− mice develop spontaneous tumors, including lymphomas and carcinomas at high rates (i.e. 27%, and 43%, respectively), indicating that Tnk1/Kos1 is a tumor suppressor. Tissues from Tnk1/Kos1-null mice exhibit proportionally higher levels of basal and growth factor-stimulated Ras activation.² Mechanistically, Tnk1/Kos1 requires either or both Y277 and Y287 sites to be intact for enzymatic activity and phosphorylation of its substrate, growth factor receptor binding protein 2 (Grb2). Data indicate that following tyrosine phosphorylation of Grb2 by Tnk1/Kos1, the Grb2-Sos1 guanine exchange factor (GEF) complex that mediates growth factor stimulated Ras activation becomes disrupted, resulting in the reversal of Ras activation. Conversely, the loss of Tnk1/Kos1 activity results in constitutive activation of Ras due to prolonged stabilization/activation of the Grb2-Sos1 GEF activity. In addition, TNK1 was found to be associated with PLC-γ1, which suggests a role for Tnk1 in phospholipid signal transduction.³ Tnk1/Kos1 is the first tyrosine kinase discovered to have tumor suppressor activity, and the mechanism of spontaneous tumor formation involves constitutive, indirect activation of Ras. Thus, Ras may display “oncogenic activity” without undergoing “oncogenic” mutation.