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Shroom-binding domain found in Rho-associated coiled-coil containing protein kinase Rho-associated coiled-coil containing protein kinase (ROCK) is a serine/threonine kinase (STK) that catalyzes the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. It is also referred to as Rho-associated protein kinase or simply as Rho kinase. The ROCK subfamily consists of two isoforms, ROCK1 and ROCK2, which may be functionally redundant in some systems, but exhibit different tissue distributions. Rho-associated protein kinase 1 (ROCK1) is also called renal carcinoma antigen NY-REN-35, Rho-associated, coiled-coil-containing protein kinase 1, ROCK-I, p160 ROCK-1, or p160ROCK, is preferentially expressed in the liver, lung, spleen, testes, and kidney. It mediates signaling from Rho to the actin cytoskeleton. It is implicated in the development of cardiac fibrosis, cardiomyocyte apoptosis, and hyperglycemia. Mice deficient in ROCK1 display eyelids open at birth (EOB) and omphalocele phenotypes due to the disorganization of actin filaments in the eyelids and the umbilical ring. Rho-associated protein kinase 2 (ROCK2), also called Rho kinase 2, Rho-associated, coiled-coil-containing protein kinase 2, ROCK-II, or p164 ROCK-2, is more prominent in brain and skeletal muscle. It is implicated in vascular and neurological disorders, such as hypertension and vasospasm of the coronary and cerebral arteries. Mice deficient in ROCK2 show intrauterine growth retardation and embryonic lethality because of placental dysfunction. ROCK subfamily proteins contain an N-terminal extension, a catalytic kinase domain, a coiled-coil (CC) region encompassing a Rho-binding domain (RBD), and a pleckstrin homology (PH) domain. ROCK is auto-inhibited by the RBD and PH domain interacting with the catalytic domain. It is activated via proteolytic cleavage, binding of lipids to the PH domain, or binding of GTP-bound RhoA to the CC region. More recently, the Shroom family of proteins have been identified as an additional regulator of ROCK. This model corresponds to the Shroom-binding domain (SBD) of ROCK, which forms a parallel coiled coil with the Shroom domain 2 (SD2) of Shroom.
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