| Modification Notes |
Myosin, the major component of thick muscle filaments, is a long asymmetric molecule containing a globular head and a long tail. Activation of smooth and cardiac/ventricular muscle primarily involves pathways which increase calcium and Myosin phosphorylation, resulting in contraction. In vertebrate striated muscle, Myosin is composed of two heavy chains and four light chains. There are two distinct types of light chains: the phosphorylatable, regulatory or MLC2 type, and the non-phosphorylatable, alkali or MLC1 and MLC3 types. The role of Myosin alkali light chains in vertebrate skeletal muscle is poorly understood, although alkali light chains in smooth muscle may be involved with the active site of Myosin. Several Myosin alkali light chains have been identified and include MYL1, MYL3, MYL4 and MYL6. |