MST1 (STK4) Proteins

Protein Information

STK4 (MST1) is a serine/threonine kinase which may be involved in apoptosis. It is possible that this protein induces the chromatin condensation observed in this process. STK4 is a stress-activated, pro-apoptotic kinase which, following caspase-cleavage, enters the nucleus and induces chromatin condensation followed by internucleosomal DNA fragmentation. It is a key component of the Hippo signaling pathway which plays a pivotal role in organ size control and tumor suppression by restricting proliferation and promoting apoptosis. The core of this pathway is composed of a kinase cascade wherein STK3/MST2 and STK4/MST1, in complex with its regulatory protein SAV1, phosphorylates and activates LATS1/2 in complex with its regulatory protein MOB1, which in turn phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ. Phosphorylation of YAP1 by LATS2 inhibits its translocation into the nucleus to regulate cellular genes important for cell proliferation, cell death, and cell migration. STK3/MST2 and STK4/MST1 are required to repress proliferation of mature hepatocytes, to prevent activation of facultative adult liver stem cells (oval cells), and to inhibit tumor formation.

Synonyms

AI447339; AU020804; EC 2.7.11.1; Kas-2; kinase MST1; kinase responsive to stress 2; KRS2; Mammalian STE20-like protein kinase 1; mammalian sterile 20-like 1; MST1; MST-1; MST1/C; MST1/N; serine/threonine kinase 4; serine/threonine-protein kinase 4; Serine/threonine-protein kinase 4 18kDa subunit; Serine/threonine-protein kinase 4 37kDa subunit; Serine/threonine-protein kinase Krs-2; STE20-like kinase MST1; sterile 20-like kinase 1; STK4; TIIAC; Yeast Sps1/Ste20-related kinase 3; YSK3