CD160 is a 27kD member of the immunoglobulin superfamily of molecules. It is expressed on select hematopoietic cell types, including CD56dim CD16+ cytotoxic NK cells, CD8+ CD28- effector T cells, D/G T cells, and restricted CD4+ T cells. It is a receptor for HLA-C molecules, and its engagement induces CD160+ NK cells to both secrete IFN-G plus TNF-A and initiate a cytotoxic program. Human CD160 was originally identified as a 155aa proprotein aa27-181. It contains a 132aa mature region aa27-159 and a C-terminal prosegment that is cleaved to create a GPI linkage. The mature region possesses one V-type Ig-like domain aa27-122. CD160 is found as a soluble, disulfide-linked 80kD multimer (likely trimer) that is generated by proteolysis of the GPI-linked form. This 80kD form, plus others, are highly resistant to reduction. There is also a 100-110kD multimeric transmembrane (TM) form that is associated with activated NK cells. It contains a 55aa substitution for aa180-181, and shows a 20aa TM segment between aa163-182. The TM form appears to have a splice variant that lacks aa25-133. Over aa27-159, human CD160 shares 62% aa identity with mouse CD160.