About MYL / Myosin Light Chain:
Myosin light chains were discovered by a Chinese Biochemist, and is a light chain of myosin as opposed to the heavy chain. Myosins are a superfamily of motor proteins that are especially prevalent in muscle contraction which is a necessary movement in humans and other mammals.
Myosin light chains belong to the EF-hand family. This is a family of Ca2+ binding proteins. Then contain two of these motifs. They have been classed in two groups which are essential MLC (MLC1 or ELC) and regulatory MLC (MLC2 or RLC). The former of these has a molecular mass of 22 and the latter has a molecular mass of 19kDa.
MLC2 contains a serine residue that isn’t found in MLC1, making them slightly structurally different.
Myosin Light Chain Function
Amino acids within the MLC’s allow for the regulation of changes from compacted to elongated form. This is done by a Ca2+ mediated phosphorylation mechanism. MLC1 has a N-terminal sequence that is able to bind actin, which contributes to the production of force.
Myosin heavy chains (MHC) are different in both structure and function from an MLC. However, associating MLCs with the neck region of MHC’s is necessary for the macromolecular complexes resulting in myosin to assemble. MLC’s can interact with the a-helical neck region of MHC molecule and it stabilizes the complex entirely. For this reason, the two cannot be entirely separated and are needed together, despite being slightly different.