Expression of non-muscle type myosin heavy polypeptide 9 (MYH9) in mammalian cells

Myosin is a functional protein associated with cellular movement, cell division, muscle contraction and other functions. Members of the myosin super-family are distinguished from the myosin heavy chains that play crucial roles in cellular processes. Although there are many studies of myosin heavy chains in this family, there are fewer on non-muscle myosin heavy chains than of muscle myosin heavy chains. Myosin is classified as type I (myosin I) or type II (myosin II). Myosin I, called unconventional myosin or mini-myosin, has one head, while myosin II, called conventional myosin, has two heads. We transfected myosin heavy polypeptide 9 (MYH9) into HeLa cells as a fusion protein with enhanced green fluorescent protein (EGFP) and analyzed the localization and distribution of MYH9 in parallel with those of actin and tubulin. The results indicate that MYH9 colocalizes with actin stress fibers. Since it has recently been shown by genetic analysis that autosomal dominant giant platelet syndromes are MYH9-related disorders, our development of transfected EGFP-MYH9 might be useful for predicting the associations between the function of actin polymerization, the MYH9 motor domain, and these disorders.