Cofilin
ADF/cofilin is a family of actin-binding proteins which disassembles actin filaments. Three highly conserved and highly (70%-82%) identical genes belonging to this family have been described in human and mice:
- CFL1, coding for cofilin 1 (non-muscle, or n-cofilin)
- CFL2, coding for cofilin 2 (found in muscle: m-cofilin)
- DSTN, coding for destrin, also known as ADF or actin depolymerizing factor
Actin-binding proteins regulate assembly and disassembly of actin filaments. Cofilin, a member of the ADF/cofilin family is actually a protein with 70% sequence homology to ADF, making it part of the ADF/cofilin family of small ADP-binding proteins. The protein binds to actin monomers and filaments, G actin and F actin, respectively. Cofilin causes depolymerization at the minus end of filaments, thereby preventing their reassembly. The protein is known to sever actin filaments by creating more positive ends on filament fragments. Cofilin/ADF(destrin) is likely to sever F-actin without capping and prefers ADP-actin. These monomers can be recycled by profilin, activating monomers to go back into filament form again by an ADP-to-ATP exchange. ATP-actin is then available for assembly.