Actin is a protein that contributes to the properties of other cells and muscles. You will find that Actin exists within two forms: F-actin, polymeric fibrous actin, and G-actin, monomeric globular actin.
The difference between F-act and G-actin is that G-actin is globular while F-actin is filamentous.
Our muscles have two long strands of actin molecules that look similar in shape to beads in a row. They’re twisted together and form myosin. Actin is the protein that is found in abundance in muscle.
Actin monomer is made up of two primary domains, and these contain two subdomains. Each of these four subdomains forms a flatter molecule. There is also a large cleft that develops between the two significant domains of actin.
Actin is an ATPase. This means that as an enzyme, it hydrolyses ATP. You can characterize these enzymes by their slow reaction rates.
The function of actin is that when a signal is sent to contract muscles, actin and myosin are both activated. The Myosin will work as the ‘motor’ and hydrolyze the ATP.
The energy that is release travels along the actin filaments (beadlike structure) and causes both filaments to move past each other.
There are a further two chemicals involved in this process; Troponin and tropomyosin. These regulate the fusion between the actin and myosin.
Actin also acts in other cellular processes, including cell division in the cytokinesis, cell mobility vesicle and organelle movement, cell signalling, and establishing and maintaining cell junctions and cell shapes.