Killer cell lectin-like receptor K1 (NKG2D) (NKG2D)

The Killer cell lectin-like receptor K1, commonly known as NKG2D, is a type II transmembrane protein belonging to the NKG2 family of C-type lectin-like receptors, encoded by the KLRK1 gene on chromosome 12p13.2. It functions as an activating and costimulatory receptor primarily expressed on natural killer (NK) cells, CD8+ T cells, and γδ T cells, where it recognizes stress-inducible ligands such as MICA, MICB, and ULBPs on the surface of virus-infected, transformed, or stressed cells. Upon ligand binding, NKG2D associates with the adaptor protein DAP10/DAP12, triggering signaling cascades that promote calcium influx, cytokine production (e.g., TNF-alpha), and perforin-mediated cytotoxicity, thereby enabling immunosurveillance against tumors and pathogens. In adaptive immunity, it amplifies T-cell receptor signaling in CD8+ T cells. Dysregulation of NKG2D expression or polymorphisms in KLRK1 are linked to altered NK cell activity, increased cancer risk, autoimmune disorders like celiac disease, and susceptibility to infections such as cowpox. Although no approved drugs directly target NKG2D, its role in recognizing stressed cells positions it as a promising therapeutic target for enhancing anti-tumor immunity or modulating immune responses in cancer and infectious diseases.

Other names

NKG2DKiller cell lectin-like receptor subfamily K member 1

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