Final answer:
CD3 cytoplasmic tails contain sequences called signal sequences that direct the receptor to the cytoplasm.
Step-by-step explanation:
Immunor tyrosine-based activation motifs (ITAMs) are sequences found in the cytoplasmic tails of CD3. ITAMs are brief sequences of amino acids that are essential for signal transduction in the activation of immune cells.
The ITAMs on the cytoplasmic tails of CD3 proteins (CD3γ, CD3δ, CD3ε, and CD3ζ) are phosphorylated in the context of the CD3 complex, which is linked to the T-cell receptor (TCR), when the TCR interacts with antigen-presenting cells.
This phosphorylation event sets off subsequent signalling pathways that activate T cells and elicit an immunological response. The cytoplasmic tails of the CD3 complex, which include ITAM, are essential for conveying signals that synchronise T-cell activation and the adaptive immunological response.