NKG2

NKG2 is a family of receptors belonging to the C-type lectin-like receptor family, primarily expressed on natural killer (NK) cells, subsets of T cells, and some myeloid cells. These receptors play a crucial role in the immune system, particularly in the recognition and response to infected, stressed, or transformed cells, including tumor cells. NKG2 receptors are involved in the regulation of NK cell activity by mediating activating or inhibitory signals, depending on the specific receptor subtype.

There are several members of the NKG2 family, which are categorized based on their signaling properties. The activating receptors, such as NKG2D, recognize stress-induced ligands on target cells and stimulate NK cell cytotoxicity and cytokine production. Conversely, inhibitory NKG2 receptors, such as NKG2A, bind to human leukocyte antigen (HLA) class I molecules, delivering signals that suppress NK cell activation to prevent unintended damage to healthy cells.

Structurally, NKG2 receptors typically form heterodimers with adaptor proteins like DAP12 (for activating receptors) or CD94 (forming heterodimers with NKG2A or NKG2C). The NKG2-DAP12 complex transmits activating signals upon ligand engagement, while NKG2-CD94 complexes usually provide inhibitory signals.

NKG2 receptors are significant in immune surveillance, particularly in detecting cellular stress during infections and tumorigenesis. Their interactions with ligands influence immune responses and have therapeutic potential in cancer immunotherapy and infectious diseases. Understanding the balance between activating and inhibitory NKG2 signals helps in developing strategies to modulate immune responses for improved clinical outcomes.