Several myosin class II heavy chain genes in human are associated with myopathies of various types, including cardiomyopathy (FBhh0000422) and proximal myopathy and ophthalmoplegia (FBhh0000424). In flies there is one gene, Mhc, orthologous to ten genes in humans that encode forms of muscle myosin class II heavy chain. (The fly gene zip is orthologous to the non-muscle myosin class II heavy chain genes.)
Classical amorphic and hypomorphic alleles, RNAi targeting constructs, and alleles caused by insertional mutagenesis have been generated for the Mhc gene. Phenotypes of amorphic alleles of Mhc range from lethality to flight defective; defects in myofibrils and sarcomeres are observed. Extensive genetic and physical interactions of Dmel\Mhc have been described; see below and in the Mhc gene report.
[updated Nov. 2016 by FlyBase; FBrf0222196]
Myosin heavy chains (MYHCs) are ubiquitous actin-based motor proteins that convert the chemical energy derived from hydrolysis of ATP into mechanical force that drives diverse motile processes, including cytokinesis, vesicular transport, and cellular locomotion, in eukaryotic cells. [from MIM:160730; 2016.10.31]
Myosin heavy chains (MYHCs) in human have been divided into 9 to 11 classes. Class II, or 'conventional,' MYHCs include the extensively studied group of sarcomeric MYHCs that self associate to form filaments and function enzymatically to promote contraction in striated (cardiac and skeletal) muscles. Muscle myosin is a heterohexamer consisting of 2 myosin heavy chains and 2 associated nonidentical pairs of myosin light chains. The 7 MYHC isoforms that predominate in mammalian skeletal muscles include 2 developmental isoforms, MYHC-embryonic (MYH3) and MYHC-perinatal (MYH8); 3 adult skeletal muscle isoforms, MYHC IIa (MYH2), MYHC IIb (MYH4), and MYHC IIx/d (MYH1); and MYHC-beta/slow (MYH7), which is also expressed in cardiac muscle. MYHC-extraocular (MYH13) is expressed primarily in extrinsic eye muscles. [from MIM:160730; 2016.10.31]
Ortholog of human muscle myosin heavy chain genes, class II (1 Drosophila to 10 human).
