Description
Fas and Fas Ligand (FasL) belong to the TNF superfamily and are type I and type II transmembrane proteins, respectively. The Fas molecule is comprised of 319 amino acids of which 145 amino acids constitute the cytoplasmic region, 17 amino acids the transmembrane domain and 157 amino acids the extracellular region. The extracellular portion of Fas is called sFasR. Binding of FasL to Fas triggers apoptosis in Fas-bearing cells. The mechanism of apoptosis involves recruitment of pro-caspase 8 through an adaptor molecule called FADD and processing of the pro-enzyme to active forms. These active caspases then cleave various cellular substrates leading to the eventual cell death. sFasR is capable of inhibiting FasL-induced apoptosis by acting as a decoy receptor that serves as a sink for FasL