Enables microfilament motor activity. Involved in cardiac muscle contraction. Acts upstream of or within several processes, including adult heart development; muscle cell development; and regulation of heart contraction. Located in Z disc and stress fiber. Part of myosin complex. Is expressed in several structures, including brown fat; embryo mesenchyme; great vessel of heart; heart; and skeletal musculature. Used to study dilated cardiomyopathy; dilated cardiomyopathy 1EE; and hypertrophic cardiomyopathy 14. Human ortholog(s) of this gene implicated in atrial heart septal defect (multiple); heart conduction disease (multiple); and intrinsic cardiomyopathy (multiple). Orthologous to human MYH6 (myosin heavy chain 6). [provided by Alliance of Genome Resources, Apr 2022]