Enables several functions, including ATP binding activity; calcium-dependent ATPase activity; and identical protein binding activity. Involved in several processes, including cellular response to 3,3',5-triiodo-L-thyronine; muscle contraction; and response to heat. Located in mitochondrion and myofibril. Part of muscle myosin complex. Biomarker of congestive heart failure; hypothyroidism; and myocardial infarction. 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]