Growth factor receptor-bound protein 2-binding adaptor protein, transmembrane (GAPT)

Growth factor receptor-bound protein 2-binding adaptor protein, transmembrane (GAPT) is a novel transmembrane adaptor protein expressed predominantly in B cells and myeloid cells. It has an extracellular domain, a single transmembrane domain, and a cytoplasmic tail containing multiple motifs that bind the adaptor protein Grb2. Unlike similar adaptors such as LAT and LAB, GAPT is not phosphorylated upon B cell receptor (BCR) ligation but instead constitutively associates with Grb2 through a proline-rich region, likely binding to the SH3 domain of Grb2. GAPT's primary known physiological role is negatively regulating B cell proliferation after BCR stimulation and maintaining normal numbers of marginal zone (MZ) B cells. Targeted disruption in mice enhances B cell proliferation and increases serum levels of certain immunoglobulin isotypes, but does not significantly impact B cell development or the classic MAPK pathway. There is no evidence currently linking GAPT to human disease pathogenesis, drug targeting, or use as a biomarker. Its precise molecular mechanisms and possible roles in other immune cell types require further study[1].

Other names

Protein GAPTC5orf29FLJ33641GRB2-binding adapter protein, transmembraneGrowth factor receptor-bound protein 2-binding adapter protein, transmembraneGRB2-binding transmembrane adaptor