Fas receptor

The Fas receptor (also known as CD95, APO-1, or TNFRSF6) is a protein that plays a crucial role in the regulation of programmed cell death, or apoptosis. It is a member of the tumor necrosis factor receptor (TNFR) superfamily and is encoded by the FAS gene in humans.

Structure

The Fas receptor is a type I transmembrane protein that consists of an extracellular domain, a transmembrane domain, and a cytoplasmic domain. The extracellular domain is responsible for binding to its ligand, Fas ligand (FasL), while the cytoplasmic domain contains a death domain that is essential for transmitting apoptotic signals.

Function

The primary function of the Fas receptor is to induce apoptosis in cells. This process is critical for maintaining homeostasis and eliminating cells that are damaged, infected, or potentially cancerous. The Fas receptor is activated when it binds to Fas ligand, which is expressed on the surface of certain immune cells, such as T cells.

Apoptotic Signaling Pathway

Upon binding of Fas ligand to the Fas receptor, a conformational change occurs, leading to the recruitment of the adaptor protein FADD (Fas-associated death domain). FADD then recruits procaspase-8, forming the death-inducing signaling complex (DISC). Activation of procaspase-8 initiates a cascade of caspase activation, ultimately leading to apoptosis.

Clinical Significance

Dysregulation of Fas-mediated apoptosis can contribute to various diseases. For example, reduced Fas signaling can lead to autoimmune diseases, where the immune system fails to eliminate self-reactive cells. Conversely, excessive Fas signaling can contribute to neurodegenerative diseases and tissue damage in conditions such as hepatitis.

Related Pages

• Apoptosis
• Fas ligand
• Caspase
• Tumor necrosis factor receptor
• Autoimmune disease