Serine/Threonine Kinase 3 (STK3)

Protein kinase activation is a frequent response of cells to treatment with growth factors, chemicals, heat shock, or apoptosis-inducing agents. This protein kinase activation presumably allows cells to resist unfavorable environmental conditions. The yeast 'sterile 20' (Ste20) kinase acts upstream of the mitogen-activated protein kinase (MAPK) cascade that is activated under a variety of stress conditions. MST2 was identified as a kinase that is activated by the proapoptotic agents straurosporine and FAS ligand. Sequence analysis indicated that, like STK4, the deduced 491-amino acid STK3 protein contains an N-terminal catalytic domain characteristic of STKs. This N-terminal domain is nearly identical to that of STK4, but the C terminus shares only 60% amino acid identity.