KLRK1 Human

Killer Cell Lectin-Like Receptor Subfamily K, Member 1 (KLRK1), also known as NKG2D, is a protein encoded by the KLRK1 gene. This protein is a member of the C-type lectin family and plays a crucial role in the immune system, particularly in the function of natural killer (NK) cells and certain T cells .

The KLRK1 gene is located on chromosome 12p13.2 and encodes a type II transmembrane protein characterized by an extracellular C terminus and a C-type lectin domain . The protein is expressed as a major 1.8-kb and a minor 3.2-kb transcript in NK cell lines and some T-cell lines .

KLRK1, or NKG2D, is an activating receptor that triggers NK cells and costimulates CD8-positive T cells. It is normally absent from almost all CD4-positive T cells but is present on most gamma/delta T cells . The receptor binds to a diverse family of ligands, including MHC class I chain-related A and B proteins and UL-16 binding proteins . These ligand-receptor interactions result in the activation of NK and T cells, promoting cytolytic responses against tumor cells and virus-infected cells .

The surface expression of KLRK1 ligands is crucial for the recognition of stressed cells by the immune system. This makes KLRK1 and its ligands therapeutic targets for the treatment of immune diseases and cancers . The receptor’s ability to activate immune responses against tumor cells highlights its potential in cancer immunotherapy .

Research on KLRK1 has focused on its role in immune regulation and its potential therapeutic applications. Studies have shown that NKG2D is expressed on gamma/delta T cells, CD8-positive T cells, and NK cells, and its interaction with ligands like MICA can activate cytolytic responses against tumor cells . This receptor-ligand interaction is a promising target for developing new cancer treatments.