STK39/A0166

Serine/threonine kinase 39 (STK39), also known as A0166, belongs to the protein kinase superfamily and may act as a mediator of stress-activated signals.

Serine/threonine kinase 39 (STK39), also known as A0166, belongs to the protein kinase superfamily and may act as a mediator of stress-activated signals. STK39 contains an N-terminal series of proline and alanine repeats (PAPA box), which may target the kinase to a specific subcellular location by facilitating interaction with intracellular proteins such as actin or actin-like proteins. It also contains a serine/threonine kinase catalytic domain, a nuclear localization signal, a consensus caspase cleavage recognition motif, and a C-terminal region. STK39 can phosphorylate itself and an exogenous substrate in vitro. It has been shown that STK39 can activate the p38 mitogen-activated protein (MAP) kinase pathway and its interaction with p38 decreases upon cellular stress, suggesting that this kinase may serve as an intermediate in the response to cellular stress. STK39 is most abundantly expressed in the brain and pancreas, however, it is also expressed in other tissues including the heart, lung, kidney, skeletal muscle, liver, placenta and testis. Full-length STK39 is expressed in the cytoplasm in transfected cells, while a mutant form corresponding to caspase-cleaved STK39 has been shown to be localized predominantly in the nucleus.