About PFN / Profilin:
Profilin serves as an actin-binding protein that is involved in the actin cytoskeleton by means of dynamic turnover and reconstruction. It is known to be essential in the temporally and spatially controlled growth of actin microfilaments. This is essential for biological processes such as organ development and wound healing capability, as well as supporting the immune system by identifying and attacking infectious intruders by cells.
It was discovered by Lars Carlsson in the ealy 1970s, considered the first actin monomer binding protein. It was then considered to sequester actin monomers and release them in order to provide accessibility for fast actin polymer growth and more.
The human genes are PFN1, PFN2, PFN3, PFN4 and PFN5.
Profilin is also the major allergen found in pollen and grass, as well as birch. It enhances actin growth in two major functions. The first is profilin-actin complex being fed into the actin polymers like WASP, VASP and formin. It also binds to monomeric actin which occupies an actin-actin contact site.
Profilins are present as single genes in insects, worms and even yeast, and multiple genes in plants and many other organisms. In mammals, for example, four profilin isoforms have been found. It is also apparent in most tissues as profilin-II is predominant in both kidney and brain organs.
Profilin is also known to bind variants of membrane phospholipids. This interaction is a sequestration of profilin in its inactive form, which is then released by action of an enzyme, in this case, phospholipase C.