DRAKS, NOVEL SERINE THREONINE KINASES RELATED TO DEATH-ASSOCIATED PROTEIN-KINASE THAT TRIGGER APOPTOSIS/

The present study describes the cloning of two novel serine/threonine kinases termed DRAK1 and DRAK2, whose catalytic domains are related to that of death-associated protein kinase, a serine/threonine kinase in volved in apoptosis, Both DRAKs are composed of the N-terminal catalyt ic domain and the C-terminal domain that is responsible for regulation of kinase activity. DRAK1 and DRAK2 show 59.7% identity and display u biquitous expression. An in vitro kinase assay revealed that both DRAK s are autophosphorylated and phosphorylate myosin light chain as an ex ogenous substrate, although the kinase activity of DRAK2 is significan tly lower than that of DRAK1. Both DRAKs are exclusively localized to the nucleus. Furthermore, overexpression of both DRAKs induces the mor phological changes of apoptosis in NIH 3T3 cells, suggesting the role of DRAKs in apoptotic signaling.