ROCK2/II (Rho-associated protein kinase 2; also Rho-kinase alpha) is a member of the AGC serine/threonine protein kinase family. ROCK2 is a downstream target of activated RhoA. Its activation results in myosin phosphorylation with subsequent muscle contraction. Human ROCK2 is 1388 amino acids (aa) in length, and appears to be present as a dimer. It contains a protein kinase domain (aa 92-354), a coiled-coil region (aa 429-1131) and a zinc-finger region (aa 1260-1315). Two isoforms show an alternate start site at M686, and a three aa substitution for the N-terminal 444 amino acids. Over aa 641-846, human ROCK2 shares 94% and 96% aa identity with mouse and canine ROCK2, respectively.