Myosin II is the so called "classical" myosin, being the first type of myosin to be discovered. Myosin II forms bipolar filaments that interact with actin filaments to produce contraction. Myosin II was first isolated from muscle but is also found in non muscle cells, and it is especially enriched in highly motile cell types such as amoebae. The myosin II molecule is composed of two heavy chains and two sets of light chains. The light chains are the Essential Light Chains (ELC) and Regulatory Light Chains (RLC). Overall activity and polymerization can be modulated by phosphorylation on the light chains and the C terminus of the heavy chains respectively.
