KLRB1 Human

Killer Cell Lectin-Like Receptor Subfamily B, Member 1 (KLRB1), also known as CD161, is a protein encoded by the KLRB1 gene in humans. This protein is a member of the C-type lectin superfamily and is predominantly expressed on the surface of natural killer (NK) cells and a subset of T cells. KLRB1 plays a crucial role in the regulation of immune responses, particularly in the context of cytotoxicity and cytokine secretion by NK cells .

KLRB1 is classified as a type II transmembrane protein, characterized by an extracellular domain with motifs typical of C-type lectins, a transmembrane domain, and a cytoplasmic domain. The extracellular domain is responsible for ligand binding, while the cytoplasmic domain is involved in signal transduction. KLRB1 functions as an inhibitory receptor on NK cells, modulating their cytotoxic activity upon engagement with its ligand, Lectin-Like Transcript-1 (LLT1) .

The expression of KLRB1 is primarily found on NK cells and certain T cell subsets, including CD8+ T cells. It is also expressed in various tissues such as the spleen, blood, and mucosal surfaces. The regulation of KLRB1 expression is influenced by various factors, including cytokines and cellular activation states .

KLRB1 plays a significant role in the immune system by regulating the activity of NK cells. Upon binding to its ligand LLT1, KLRB1 transmits inhibitory signals that reduce the cytotoxic activity of NK cells. This mechanism is essential for maintaining immune homeostasis and preventing excessive immune responses that could lead to tissue damage .

Alterations in KLRB1 expression and function have been associated with various diseases, including certain types of lymphomas and autoimmune disorders. Understanding the role of KLRB1 in these conditions could provide insights into potential therapeutic targets for modulating immune responses .