CD8
CD8 (gene symbol CD8A, also known as p32 or CD8alpha) is an integral membrane glycoprotein that acts as a coreceptor for the T-cell receptor on cytotoxic T lymphocytes. It binds MHC class I molecules presented by antigen presenting cells and supports cell-cell interaction in the immune response. Browse Assay Genie's current range of CD8 research reagents below, or read on for the biology behind the target.
CD8 is an integral membrane glycoprotein with an essential role in the immune response. In T-cells it functions primarily as a coreceptor for the MHC class I molecule:peptide complex. Class I peptides are derived from cytosolic proteins, whereas class II peptides derive from extracellular proteins. CD8 interacts simultaneously with the T-cell receptor (TCR) and the MHC class I proteins presented by antigen presenting cells. In turn, it recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. LCK then phosphorylates various substrates and initiates intracellular signalling pathways that lead to lymphokine production, motility, adhesion and activation of cytotoxic T-lymphocytes (CTLs). This mechanism enables CTLs to recognise and eliminate infected cells and tumour cells.
The coreceptor works either as a homodimer of two alpha chains or as a heterodimer of one alpha and one beta chain. Both chains share significant homology with immunoglobulin variable light chains, and the CD8 alpha chain is encoded by the CD8A gene, which belongs to the HGNC groups of CD molecules and V-set domain containing proteins. In NK-cells, CD8 alpha homodimers at the cell surface provide a survival mechanism that allows conjugation and lysis of multiple target cells. CD8 alpha homodimers also promote the survival and differentiation of activated lymphocytes into memory CD8 T-cells.
Multiple transcript variants encoding different isoforms have been found for the CD8 gene. The major isoforms differ by the presence or absence of a transmembrane domain, so they are either membrane-anchored or secreted, which is consistent with the cell membrane and secreted locations recorded for the protein. Previous names include CD8 antigen, alpha polypeptide (p32) and CD8a molecule. Mouse and rat both have a Cd8a ortholog.
CD8 is found on most cytotoxic T lymphocytes and supports the activation that lets CTLs eliminate infected and tumour cells.
CD8 binds MHC class I and recruits LCK to the TCR-CD3 complex, making it a key component for studying coreceptor signalling.
Because CD8 enables CTLs to recognise infected and tumour cells, it is central to research on cell-mediated immune responses.
CD8 alpha homodimers support NK-cell survival and lysis of multiple targets, and promote differentiation of activated lymphocytes into memory CD8 T-cells.
CD8 is a coreceptor for the T-cell receptor. It binds MHC class I molecules on antigen presenting cells and recruits the kinase LCK to the TCR-CD3 complex, triggering signalling that activates cytotoxic T-lymphocytes to eliminate infected and tumour cells.
CD8 is encoded by CD8A, and is also called p32, CD8alpha, CD8 antigen alpha polypeptide and T-cell surface glycoprotein CD8 alpha chain. Several transcript variants exist; major isoforms differ by a transmembrane domain, giving membrane-anchored or secreted proteins. CD8 can form alpha homodimers or alpha-beta heterodimers.
Mouse and rat each have an ortholog named Cd8a, so the CD8 alpha chain is studied in rodent models as well as in human. Check the datasheet of any product for its validated reactivity.
Other CD molecules and immune cell markers with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P01732; product specifications from Assay Genie datasheets.