Myosin

links: reference: 8-22-2021

Myosin #

A superfamily of motor Proteins. A single myosin II contains two heavy chains of about 2000 amino acids in length. Composed of a head, neck, and tail domain:

• The base of the head of Myosin binds to active sites (holes) inside F-actin (filamentous; as opposed to G-actin, globular) (F-actin gives rise to the helix-like shape of the thin filament due to it being a polymer), allowing for movement.
  • The head also uses the enzyme myosin ATPase, activated by Ca2+, causing ATP Hydrolysis, generating force.
• The neck acts as a lever arm for the transduction of force generated by the motor domain.
  • The neck consists of light chains: the regulatory light chain and essential light chain. The former undergoes phosphorylation, changing activity of the myosin, the latter structurally stabilizes the myosin neck/head.
• The tail mediates interaction with cargo molecules or myosin subunits.

Myosin Light Chain #

Just a small subunit of myosin II.