Description
SLAM family member 5 (SLAMF5/CD84) is a type I transmembrane protein in the SLAM subgroup of the CD2 family. SLAM family proteins regulate multiple aspects of immune system function. Mature human CD84 consists of a 204 amino acid (aa) extracellular domain (ECD) with two Iglike domains,a 21 aa transmembrane segment, and a 99 aa cytoplasmic domain with two immunoreceptor tyrosinebased switch motifs (ITSMs). CD84 exhibits homophilic binding which is mediated by the N-terminal Ig-like domain. Ligation induces tyrosine phosphorylation in the cytoplasmic ITSMs which then recruit the signaling adaptor molecules SAP (SLAM-associated protein) and EAT-2(EWS/Fli1-activated transcript 2).CD84 signaling inhibits Fc epsilon RI-induced mast cell activation but enhances platelet activation. LPS-induced macrophage activation,T cell proliferation and IFN-γproduction, and the interactions between T cells and B cells that are required for germinal center formation.