Killer cell lectin-like receptor subfamily B member 1 (KLRB1)

Killer cell lectin-like receptor subfamily B member 1 (KLRB1), also known as NKR-P1A or CD161, is a type II transmembrane C-type lectin-like receptor heavily expressed on human natural killer (NK) cells as well as subsets of T cells, including NKT and certain memory T cells[2][4]. It acts predominantly as an inhibitory receptor in humans, exerting its function through recognition of the ligand LLT1 (CLEC2D), which is upregulated in response to cellular stress, infection, or transformation[4][2][1]. The receptor possesses an intracellular ITIM, and engagement with LLT1 transmits inhibitory signals that modulate NK and T cell cytotoxicity and cytokine production. Structural studies show NKR-P1A forms homodimers and interacts with the dimeric form of LLT1 in the immune synapse, facilitating signal transduction critical for discrimination between healthy and abnormal cells[1]. NKR-P1A is implicated in immune surveillance, and altered expression or function is associated with various conditions, including cancer, infection, and autoimmunity[4].

Other names

NKR-P1ACD161KLRB1CLEC5BNKRP1A

Inhibitory signaling via immunoreceptor tyrosine-based inhibitory motif (ITIM) upon ligand engagement (LLT1)