DNAX accessory molecule 1 (DNAM-1), a single-pass type I membrane protein, is also known as CD226 antigen and platelet and T cell activation antigen 1 (PTA1), which contains 2 Ig-like C2-type (immunoglobulin-like) domains. DNAM-1 is a ~65 kDa glycoprotein expressed on the surface of natural killer cells, platelets, monocytes and a subset of T cells. DNAM-1 mediates cellular adhesion to other cells bearing its ligands, CD112 and CD155, and cross-linking DNAM-1 with antibodies causes cellular activation. Furthermore, DNAM-1 can interact with PVR and PVRL2.