這個基因編碼一種蛋白質，在雙向刺激T和B細胞中起主要作用。這種蛋白質含有SH2結構域和短尾。它與信號淋巴細胞活化分子相結合，從而通過阻止含有shp-2信號轉導分子的sh2結構域進入其對接位點而起到抑制這種跨膜蛋白的作用。這種蛋白質還可以與活化的t、b和nk細胞上表達的其他相關表面分子結合，從而改變這些細胞的信號轉導途徑。該基因突變導致淋巴增生綜合征x連鎖1型或duncan病，一種罕見的免疫缺陷，其特征是極易感染eb病毒，癥狀包括嚴重的單核細胞增多癥和惡性淋巴瘤。已發現該基因編碼不同亞型的多個轉錄變體。
This gene encodes a protein that plays a major role in the bidirectional stimulation of T and B cells. This protein contains an SH2 domain and a short tail. It associates with the signaling lymphocyte-activation molecule, thereby acting as an inhibitor of this transmembrane protein by blocking the recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to its docking site. This protein can also bind to other related surface molecules that are expressed on activated T, B and NK cells, thereby modifying signal transduction pathways in these cells. Mutations in this gene cause lymphoproliferative syndrome X-linked type 1 or Duncan disease, a rare immunodeficiency characterized by extreme susceptibility to infection with Epstein-Barr virus, with symptoms including severe mononucleosis and malignant lymphoma. Multiple transcript variants encoding different isoforms have been found for this gene.