Anti-BIG1 Antibody, clone 102 clone 102, from mouse

Brefeldin A-inhibited guanine nucleotide-exchange protein 1 (UniProt: Q9Y6D6; also known as BIG1, Brefeldin A-inhibited GEP 1, ADP-ribosylation factor guanine nucleotide-exchange factor 1, p200 ARF guanine nucleotide exchange factor, p200 ARF-GEP1) is encoded by the ARFGEF1 (also known as ARFGEP1, BIG1) gene (Gene ID: 10565) in human. BIG1 is expressed in placenta, lung, heart, brain, kidney and pancreas. BIG1 activates ADP-ribosylation factor (ARF) GTPases and is involved in vesicular trafficking. It promotes the activation of ARF1/ARF3 through replacement of GDP with GTP. BIG1 is required for the maintenance of Golgi structure and this function may be independent of its GEF activity. BIG1 and BIG2 display about 74% homology in their amino acid sequence and about 90% identity in their Sec7 domains. BIG1 is phosphorylated by PKA that reduces its GEF activity. It is localized in the cytoplasm in a multiprotein complex along with BIG2. Its nuclear localization has also been reported and it contains a nuclear localization sequence (aa 711-715). In serum starved cells treated with FK506, BIG1 is essentially completely concentrated in nuclei. BIG1 is shown to be a binding partner of myosin IXb and regulates its Rho-GTPase activating protein activity. Here BIG1 and RhoA compete with each other for the binding to myosin IXb, thus resulting in the inhibition of the GAP activity by BIG1. (Ref.: Lin, S et al. (2013). Arterioscler Thromb Vasc Biol. 33(2): e31-e38).