CD40 (protein)

CD40 is a protein that is encoded by the CD40 gene in humans. It is a member of the TNF-receptor superfamily. This protein is expressed on the surface of B cells, dendritic cells, monocytes, thymocytes, and endothelial cells. It plays a crucial role in B-cell activation and differentiation, and also has important functions in the immune response to T cells.

Structure

The CD40 protein is a 277-amino acid transmembrane protein. It is composed of an extracellular domain, a transmembrane domain, and a cytoplasmic domain. The extracellular domain contains the binding site for the CD40 ligand, while the cytoplasmic domain is responsible for transmitting the signal into the cell.

Function

CD40 is a receptor that plays a vital role in the activation and differentiation of B cells. When CD40 is bound by its ligand, CD40L, it triggers a series of intracellular events that lead to B cell activation and differentiation. This process is crucial for the production of antibodies and the development of memory B cells.

In addition to its role in B cells, CD40 also has important functions in other immune cells. In dendritic cells, CD40 signaling can lead to the production of cytokines and the upregulation of co-stimulatory molecules, which are important for T cell activation. In monocytes, CD40 signaling can induce the production of pro-inflammatory cytokines and chemokines.

Clinical significance

Alterations in the CD40 pathway have been implicated in a number of diseases, including autoimmune diseases, cancer, and infectious diseases. For example, mutations in the CD40 gene have been associated with hyper IgM syndrome, a rare immunodeficiency characterized by a lack of IgG and IgA antibodies.

In cancer, CD40 signaling can have both pro-tumor and anti-tumor effects. On one hand, CD40 signaling can promote tumor growth by stimulating the production of pro-inflammatory cytokines that support tumor growth. On the other hand, CD40 signaling can also stimulate anti-tumor immune responses by activating dendritic cells and T cells.

See also

• CD40 ligand
• TNF-receptor superfamily
• B cell
• Dendritic cell
• Monocyte
• Thymocyte
• Endothelial cell