actin and myosin

what are actin and myosin

contractile proteins, the main myofilaments that form the sarcomere.

what do they do

They are the force generating proteins of the sarcomere, and they work together during the muscle contraction cycle in order to produce movement.

myosin is

the contractile protein that forms the thick filaments.

myosin location

lies mainly in the A-band and H-zone of the sarcomere and interacts with actin to create movement.

Myosin filaments are made up of

three domains: head, tail, and neck.

myosin function

mainly involves coupling hydrolysis of ATP to conformational changes in the head region of the filament that enables it bind and move along actin filaments.

actin

the contractile protein that forms the thin filaments.

Each actin microfilament is a

polymer known as F actin and is composed of individual monomeric protein subunits known as G actin. The F actin polymers twist together, and being composed of G actin subunits, gives the appearance of two strings of beads twisted together.

All actin filaments are of

the same length

actin contains

myosin binding sites, to which the myosin heads attach and 'walk' along, resulting in the contraction.