Genes in this family provide instructions for making related proteins called myosins. Myosins are often referred to as molecular motors because they use energy to move. They interact with another protein called actin; actin proteins are organized into filaments to form a network (the cytoskeleton) that gives structure to cells and can act as a track for myosin to move along. Some myosin proteins attach (bind) to other proteins and transport them within and between cells along the actin track.
Some myosins are involved in muscle contraction. These myosins interact with other myosin proteins, forming thick filaments. In muscle cells, thick filaments made up of myosin and thin filaments made up of actin compose structures called sarcomeres, which are the basic units of muscle contraction. The overlapping thick and thin filaments bind to each other and release, which allows the filaments to move relative to one another so that muscles can contract. Mutations in genes that provide instructions for making muscle myosins can cause severe abnormalities in the muscles used for movement (skeletal muscles) or in the heart (cardiac) muscle. Cardiac muscle abnormalities can lead to heart failure and sudden death.
Myosin proteins are involved in many cellular functions. Their ability to transport materials and create force through contractions make them important in the process of cell division. Myosins are also involved in cell movement. Some myosins are found in specialized structures in the inner ear known as stereocilia. These myosins are thought to help properly organize the stereocilia. Abnormalities in these myosins can cause deafness.
The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families and their member genes.
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