CD3 (immunology)

In immunology, the CD3 (cluster of differentiation 3) T-cell co-receptor helps to activate the cytotoxic T-Cell. It consists of a protein complex and is composed of four distinct chains. In mammals, the complex contains a CD3γ chain, a CD3δ chain, and two CD3ε chains. These chains associate with a molecule known as the T-cell receptor (TCR) and the ζ-chain (zeta-chain) to generate an activation signal in T lymphocytes. The TCR, ζ-chain, and CD3 molecules together comprise the TCR complex.

Structure

The CD3γ, CD3δ, and CD3ε chains are highly related cell-surface proteins of the immunoglobulin superfamily containing a single extracellular immunoglobulin domain.

Containing aspartate residues, the transmembrane region of the CD3 chains is negatively charged, a characteristic that allows these chains to associate with the positively charged TCR chains.

The intracellular tails of the CD3 molecules contain a single conserved motif known as an immunoreceptor tyrosine-based activation motif or ITAM for short, which is essential for the signaling capacity of the TCR.

CD247

T-cell surface glycoprotein CD3 zeta chain also known as T-cell receptor T3 zeta chain or CD247 (Cluster of Differentiation 247) is a protein that in humans is encoded by the CD247 gene.

Genomics

The gene is located on the long arm of chromosome 1 at location 1q22-q25 on the Crick (negative) strand. The gene is 87,896 bases in length. The encoded protein is 164 amino acids long with a predicted weight of 18.696 kiloDaltons.

Function

T-cell receptor zeta, together with T-cell receptor alpha/beta and gamma/delta heterodimers and CD3-gamma, -delta, and -epsilon, forms the T-cell receptor-CD3 complex. The zeta chain plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. Low expression of the antigen results in impaired immune response. Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.

Interactions

CD247 has been shown to interact with Janus kinase 3 and Protein unc-119 homolog.