Actin accounts for the fact that in the protein content of a cell it always represents a high percentage and its sequence is very conserved, that is, it has changed very little throughout evolution.2 3 For both reasons it can be said That its structure has been optimized. Two peculiar characteristics can be highlighted on this: it is an enzyme that hydrolyzes ATP, the "universal currency of energy" of biological processes, doing so very slowly. But at the same time it needs that molecule to maintain its structural integrity. It acquires its effective form in an almost dedicated folding process. It is also the one that establishes more interactions with other proteins of how many are found, which allows it to perform the most varied functions that reach almost all aspects of cell life. Myosin is an example of a protein that binds actin. Another example is viline, which can interweave actin into bundles or cut actin filaments, affect the concentration of calcium cation in its environment.4
Forming microfilaments in a dynamic process provides a scaffolding that gives the cell a way to quickly remodel in response to its environment or body signals, for example, improves the cell surface for absorption or adhesion supports cells to form tissues. Other enzymes, organelles such as cilia, can be anchored on this scaffold, directing the deformation of the external cell membrane that allows cell ingestion or cytokinesis. It can also produce movement, either by itself or by molecular motors. Thus contributing to processes such as intracellular transport of vesicles and organelles and muscle contraction, or cell migration, important in embryonic development, wound repair or cancer invasiveness. The evolutionary origin of this protein can be traced in prokaryotic cells, where equivalents exist. Finally it is important in the control of gene expression.
A good number of diseases are based on genetic alterations in alleles of the genes that govern the production of actin or its associated proteins, being also essential in the process of infection of some pathogenic microorganisms. Mutations in the different actin genes present in humans cause myopathies, variations in cardiac size and function and deafness. The components of the cytoskeleton are also related to the pathogenicity of intracellular bacteria and viruses, especially in processes related to the evasion of the immune system response
