Anti-SAP/SH2D1A Antibody, clone 1A9 clone 1A9, from rat

SH2 domain-containing protein 1A (UniProt O60880; also known as Signaling lymphocytic activation molecule-associated protein, SLAM-associated protein, T-cell signal transduction molecule SAP) is encoded by the Sh2d1a (also known as Xlp) gene (Gene ID 20400) in murine species. SAP/SH2D1A is a 628-amino acid (isoform A) adaptor protein expressed in T cells, natural killer (NK) cells, NK-T cells, and some B cells. SAP/SH2D1A is made up almost exclusively of a Src homology 2 (SH2) domain (a.a. 6-104) and plays an important role in multiple immune cell functions, including T helper 2 (TH2) cytokine production, T cell-dependent antibody production, follicular T helper (TFH) cell differentiation, NK-T cell development, CD8+ T cell- and NK cell-mediated cytotoxicity. SAP couples signaling lymphocytic activation molecule (SLAM) family receptors to tyrosine phosphorylation signals through its interaction with the SH3 domain of Src family protein tyrosine kinase Fyn. In addition, SAP can prevent SH2 domain-containing negative regulators, such as phosphatases SHIP-1 and SHP-1, from inactivating SLAM-related receptors by blocking their interaction with the receptors. Evidence also shows that SAP/SH2D1A regulates T cell-dependent antibody production and TFH cell differentiation independent of Fyn. SAP/SH2D1A gene is mutated and inactivated in X-linked lymphoproliferative disease, a rare human immunodeficiency characterized by an uncontrolled immune response to Epstein-Barr virus infection.