Adapter protein for several members of the tyrosine kinase receptor family. Involved in multiple signaling pathways. May be involved in coupling from immunoreceptor to Ras signaling. Acts as a negative regulator of cytokine signaling in collaboration with CBL. Binds to EPOR and suppresses EPO-induced STAT5 activation, possibly through a masking effect on STAT5 docking sites in EPOR. Suppresses PDGF-induced mitogenesis. May induce cytoskeletal reorganization via interaction with VAV3. Homodimer. Interacts with KIT/c-KIT, SHC1, EPOR, PDGFR, VAV1 and VAV3. Interacts (via N-terminal region) with SHC1. Interacts (via the phosphorylated C-terminus) with GRB2. Interacts (via its SH2 domain) with EPOR, INSR and KIT. Interacts with GRB2 after B-cell antigen receptor stimulation. Interacts (via PH domain) with VAV3. Interacts with NTRK1, NTRK2 and NTRK3 (phosphorylated); after stimulation of the receptor by its extracellular ligand and subsequent autophosphorylation of the receptor. Binds INSR, GRB2, ASB6 and CAP. Insulin stimulation leads to dissociation of CAP. Binds CBS only when SH2B2/APS has become phosphorylated. INSR binding does not depend on the phosphorylation of SH2B2/APS (By similarity). Cytoplasmic before PDGF stimulation. After PDGF stimulation, localized at the cell membrane and peripheral region. Expressed in spleen, prostate, testis, uterus, small intestine and skeletal muscle. Among hematopoietic cell lines, expressed exclusively in B-cells. Not expressed in most tumor cell lines. Tyrosine phosphorylated by JAK2, KIT and other kinases activated by B-cell receptor in response to stimulation with cytokines, IL3, IL5, PDGF, IGF1, IGF2, CSF2/GM-CSF and cross-linking of the B-cell receptor complex. Belongs to the SH2B adapter family.