CD94 is a 43/39 kD C-type lectin, also known as Kp43. It is present on all NK cells, NK-T cells, and a subset of CD8-positive T lymphocytes in most mouse strains. CD94 is a type-II transmembrane protein with an extracellular lectin-like domain and a short cytoplasmic tail. CD94 is expressed as a disulphide-linked heterodimer with a NKG2 subunit believed to mediate signal transduction. When associated with NKG2A, the complex triggers inhibition; when associated with NKG2C, the complex triggers stimulation. The receptor complex of CD94 and NKG2 receptors bind to the ligand, Qa-1, and are thought to play a role in maintaining self-tolerance in developing NK cells.