T cell receptor alpha joining 18 (TRAJ18)

T cell receptor alpha joining 18 (TRAJ18) is a gene segment encoding the Jα18 (joining alpha 18) region of the T cell receptor (TCR) alpha chain locus in humans and mice[2][3][7]. It is a short DNA sequence involved in V(D)J recombination during T lymphocyte development, serving as the canonical joining segment for the invariant TCR used by iNKT cells[6]. TRAJ18 is critical for the generation and function of invariant Natural Killer T cells, which play important roles in immune regulation and response to infections and tumors[6]. Notably, it is not itself a receptor, enzyme, transporter, or classical therapeutic target, but rather a segment used in immune cell development; hence, it is not considered a druggable target, nor is it a suitable biomarker or subject to direct therapeutic intervention[7][8]. Deletion or mutation of TRAJ18 in mouse models results in the complete absence of iNKT cells, providing a tool for immunological research[6]. The term is sometimes confused as a receptor/protein, which is incorrect; it refers to a genomic segment, and the canonical target in immune modulation would be the invariant T cell receptor containing the TRAJ18 segment, not TRAJ18 itself.

Other names

TRAJ18Traj18Jα18J alpha 18T cell receptor alpha joining segment 18