Tsolureseptoreita

Tsolureseptoreita, known in English as T-cell receptors (TCRs), are specialized membrane proteins on the surface of T lymphocytes that recognize peptide antigens presented by major histocompatibility complex (MHC) molecules. Most TCRs are αβ heterodimers, while a smaller subset are γδ TCRs. Each receptor comprises two chains (α and β, or γ and δ) with variable and constant regions; the variable domains form the antigen-binding site and contain the complementarity-determining regions that determine specificity.

Diversity of TCRs arises through V(D)J recombination during T cell development, with additional junctional diversity from nucleotide insertions and deletions. This extensive repertoire enables T cells to recognize a wide range of peptide antigens derived from pathogens or altered self proteins.

Antigen recognition involves peptide fragments bound to MHC on antigen-presenting cells. The TCR interacts with the peptide-MHC complex in a manner that is highly specific, and the engagement of co-receptors—CD4 with MHC class II or CD8 with MHC class I—stabilizes the interaction and supports signaling. Initiation of TCR signaling requires the CD3 complex and the zeta chain, which contain ITAM motifs that recruit kinases; full T cell activation typically needs a secondary co-stimulatory signal, such as CD28 binding to B7 molecules.

Developmentally, thymic selection shapes the TCR repertoire. Positive selection favors T cells whose TCRs can recognize self-MHC, whereas negative selection eliminates those with strong reactivity to self-antigens, contributing to central tolerance.

Clinically, TCRs are central to adaptive immunity and are targets in immunotherapies, including TCR-engineered T cells and various T cell-based vaccines. Dysregulation of TCR signaling or specificity can contribute to autoimmunity, immunodeficiency, or cancer.