CD8A

CD8A is a gene that encodes the alpha chain of the CD8 protein, a type of T cell co-receptor. The CD8 protein is primarily expressed on the surface of cytotoxic T cells and Natural Killer T (NKT) cells, and plays a crucial role in T cell activation and immune response.

Structure[edit | edit source]

The CD8A gene is located on the short (p) arm of chromosome 2 at position 21. The protein encoded by this gene is a member of the immunoglobulin superfamily, and is composed of an extracellular IgV-like domain, a transmembrane domain, and a cytoplasmic tail.

Function[edit | edit source]

The primary function of the CD8A protein is to act as a co-receptor for the T cell receptor (TCR). By binding to the Major Histocompatibility Complex (MHC) class I molecules on antigen-presenting cells, CD8A enhances the sensitivity of the TCR to antigen, thereby promoting T cell activation.

In addition to its role in T cell activation, CD8A also plays a role in the development and differentiation of T cells in the thymus. It is involved in the positive selection of cytotoxic T cells, and in the suppression of the immune response by regulatory T cells.

Clinical significance[edit | edit source]

Mutations in the CD8A gene have been associated with various immune disorders, including autoimmune diseases and immunodeficiency syndromes. For example, a deficiency in CD8A can lead to a decrease in the number of cytotoxic T cells, resulting in an increased susceptibility to viral infections.

Furthermore, the expression of CD8A is often used as a marker for cytotoxic T cells in immunohistochemical studies. It can also be used to distinguish between different types of lymphoma and leukemia, as these diseases often have distinct patterns of CD8A expression.

File:CD8A protein structure.png

The structure of the CD8A protein. Image from Wikimedia Commons.