T-cell surface glycoprotein CD8 alpha chain (Cluster of Differentiation 8a), is a protein encoded by ''CD8A''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
The
CD8
CD8 (cluster of differentiation 8) is a transmembrane protein, transmembrane glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). Along with the TCR, the CD8 co-receptor plays a role in T cell Cell signaling, signaling and aid ...
protein is a cell surface
glycoprotein
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...
found on most
cytotoxic T lymphocytes that mediates efficient
cell-cell interactions within the
immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
. The CD8, acting as a
coreceptor, and the
T-cell receptor
The T-cell receptor (TCR) is a protein complex, located on the surface of T cells (also called T lymphocytes). They are responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. ...
on the T lymphocyte recognize
antigen
In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.
...
displayed by an
antigen-presenting cell
An antigen-presenting cell (APC) or accessory cell is a Cell (biology), cell that displays an antigen bound by major histocompatibility complex (MHC) proteins on its surface; this process is known as antigen presentation. T cells may recognize the ...
(APC) in the context of
class I MHC molecules. The functional coreceptor is either a
homodimer
In biochemistry, a protein dimer is a macromolecular complex or protein multimer, multimer formed by two protein monomers, or single proteins, which are usually Non-covalent interaction, non-covalently bound. Many macromolecules, such as proteins ...
composed of two alpha chains, or a
heterodimer composed of one alpha and one beta chain. Both alpha and beta chains share significant
homology to
variable domain of
immunoglobulin light chains. This gene encodes the CD8 alpha chain isoforms. Two alternative transcripts encoding distinct isoforms, one
membrane associated and one
secreted, have been identified.
Interactions
CD8A has been shown to
interact with:
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CD3D,
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HLA-A
HLA-A is a group of human leukocyte antigens (HLA) that are encoded by the ''HLA-A'' locus (genetics), locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one o ...
,
See also
* Cluster of differentiation
The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as CD) is a protocol used for the identification and investigation of cell surface molecules providing targets for immunophe ...
References
Further reading
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External links
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Clusters of differentiation
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