GLUT4 Enhancer Factor (GEF)

SLC2A4RG is a transcriptional regulator of the GLUT4 gene.The deduced 387-amino acid protein has a calculated molecular mass of 46 kD. HDBP1 contains a central serine-rich region, followed by a proline-rich region and a C2H2-type zinc finger domain. It also has 3 regions that are highly conserved with HDBP2 (ZNF395) and mouse glucocorticoid-induced gene-1 (Gig1), as well as 2 NLSs and 3 nuclear export signals (NESs). Northern blot analysis detected a 1.8-kb transcript in all tissues examined. Fluorescence-tagged HDBP1 localized in the cytoplasm of HeLa cells and a human neuronal cell line, and the localization shifted to nuclei following nuclear export inhibition. Site-directed mutagenesis indicated that the third NES and the second NLS of HDBP1 were functional.