CD1

CD1 (cluster of differentiation 1) is a family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are related to the class I MHC molecules, and are involved in the presentation of lipid antigens to T cells. However their precise function is unknown.

Structure

CD1 molecules are structurally similar to the major histocompatibility complex (MHC) class I molecules, however, the CD1 lipid antigen presentation pathway is distinct from the classical MHC peptide antigen presentation pathway. CD1 molecules are transmembrane proteins that have a heavy chain and a light chain. The heavy chain contains three domains: alpha1, alpha2, and alpha3. The alpha1 and alpha2 domains form the antigen-binding groove, which is composed of six pockets (A' to F').

Function

CD1 proteins are involved in the presentation of lipid antigens to T cells. Lipid antigens can be presented by CD1 molecules to T cells, which can then initiate an immune response. The precise function of CD1 molecules is still unknown, but they are thought to play a role in the immune response to infections and in autoimmune diseases.

Types

There are five types of human CD1 molecules: CD1a, CD1b, CD1c, CD1d, and CD1e. CD1a, CD1b, and CD1c present foreign lipid antigens, while CD1d presents self lipid antigens. CD1e is involved in lipid antigen processing.

Clinical significance

CD1 molecules have been implicated in a variety of diseases, including tuberculosis, leprosy, and autoimmune diseases. They are also being investigated for their potential use in cancer immunotherapy.

See also

• Cluster of differentiation
• Antigen-presenting cell
• Major histocompatibility complex
• T cell
• Autoimmune disease
• Cancer immunotherapy

References

CD1 Resources
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