Serine/Threonine Kinase 39 (STK39)

STK39 encodes a serine/threonine kinase that is thought to function in the cellular stress response pathway. The kinase is activated in response to hypotonic stress, leading to phosphorylation of several cation-chloride-coupled cotransporters. The deduced 547-amino acid protein has a calculated molecular mass of 59.6 kD. STK39 contains an N-terminal series of proline and alanine repeats (PAPA box), followed by a serine/threonine kinase catalytic domain, a nuclear localization signal, a consensus caspase cleavage recognition motif, and a C-terminal region. Northern blot analysis detected ubiquitous expression of a 3.8-kb transcript, with most abundant expression in brain and pancreas. Western blot analysis of mouse tissues detected a protein of about 60 kD in all tissues examined.