Involved in FCER1 (high affinity immunoglobulin epsilon receptor)-mediated signaling in mast cells. May also be involved in BCR (B-cell antigen receptor)-mediated signaling in B-cells and FCGR1 (high affinity immunoglobulin gamma Fc receptor I)-mediated signaling in myeloid cells. Couples activation of these receptors and their associated kinases with distal intracellular events through the recruitment of GRB2. When phosphorylated, interacts with GRB2. May also interact with SOS1, GAB1 and CBL. Present in lipid rafts. Highly expressed in spleen, peripheral blood lymphocytes, and germinal centers of lymph nodes. Also expressed in placenta, lung, pancreas and small intestine. Present in B-cells, NK cells and monocytes. Absent from T-cells (at protein level). Phosphorylated on tyrosines following cross-linking of BCR in B-cells, FCGR1 in myeloid cells, or FCER1 in mast cells; which induces the recruitment of GRB2. May be polyubiquitinated. LAT2 is located in the Williams-Beuren syndrome (WBS) critical region. WBS results from a hemizygous deletion of several genes on chromosome 7q11.23, thought to arise as a consequence of unequal crossing over between highly homologous low-copy repeat sequences flanking the deleted region. Haploinsufficiency of LAT2 may be the cause of certain cardiovascular and musculo-skeletal abnormalities observed in the disease.