SLAM Family Member 6 (SLAMF6) is a single-pass type I membrane protein that belongs to the SLAM subgroup of the CD2 family. Human SLAMF6/ NTB-A contains a 205 amino acid extracellular domain (ECD) with one Ig-like V-set and one Ig-like C2-set domain, a 21 amino acid transmembrane segment and an 84 amino acid cytoplasmic domain, with two immunoreceptor tyrosine-based switch motifs. SLAMF6 is a homodimer. SLAMF6 can interact with PTN6 and, upon phosphorylation, with PTN11 and SH2D1A/SAP. Phosphorylation-dependent NTB-A association with SAP is required for full production of IFN-γ by NK cells and independent of EAT-2 binding. It Triggers cytolytic activity only in natural killer cells (NK) expressing high surface densities of natural cytotoxicity receptors. On B cells, NTB-A modulates immunoglobulin class switching and the balance between tolerance and autoimmunity.