MYH9 antibody

Myosins belong to a superfamily of actin based motor proteins comprising to date at least 15 classes. There are two main groups of myosins: the conventional (class II) and the unconventional myosins. Myosin IIA (nonmuscle) is a relatively abundant, widespread two headed myosin composed of an N-terminal motor domain, a light chain binding neck region, a coiled-coil region, and a non helical C-terminal domain. It forms a heterohexamer composed of a pair of heavy chains and two pairs of light chains. The vertebrate myosin II class members include muscle (sarcomeric and smooth) and nonmuscle (cytoplasmic) myosins. The nonmuscle myosin II class contains two isoforms: IIA and IIB, which exhibit 85% and 72% amino acid identity in the motor domain and the rod, respectively. Varying ratios of the two isoforms are expressed in different cells and tissues. Some cells express only a single isotype: e.g. myosin IIA in human platelets, rat basophilic leukemia cells, and chicken intestinal epithelium and myosin IIB in embryonic cardiac myocytes and COS-7 cells. The two isoforms vary in their intracellular localization, enzymatic activities, and proposed functions. Three additional isoforms of IIB have been described in neurons. Another isoform, myosin IIC, seems to constitute a distinct third isoform of the nonmuscle myosins. Nonmuscle myosin II is involved in cell motility and adhesion, cytokinesis, vesicular transport, intracellular force generation, and in morphogenesis during development. Its activity is regulated by light chain and possibly heavy chain phosphorylation and by association with proteins such as Mts1. Mutations in the NMHCA gene are found in several syndromes associated with megakaryocyte/platelet/leukocyte disorders.