protein kinase C conserved region 1 (C1 domain) found in Rho-associated coiled-coil containing protein kinase 2 (ROCK2) and similar proteinsROCK2 is a serine/threonine kinase, catalyzing the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. ROCK2, also called Rho-associated protein kinase 2, Rho kinase 2, Rho-associated, coiled-coil-containing protein kinase II (ROCK-II), or p164 ROCK-2, was the first identified target of activated RhoA, and was found to play a role in stress fiber and focal adhesion formation. It is prominently expressed in the brain, heart, and skeletal muscles. It is implicated in vascular and neurological disorders, such as hypertension and vasospasm of the coronary and cerebral arteries. ROCK2 is also activated by caspase-2 cleavage, resulting in thrombin-induced microparticle generation in response to cell activation. Mice deficient in ROCK2 show intrauterine growth retardation and embryonic lethality because of placental dysfunction. ROCK proteins contain an N-terminal extension, a catalytic kinase domain, and a C-terminal extension, which contains a coiled-coil region encompassing a Rho-binding domain (RBD), a pleckstrin homology (PH) domain and a C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.