Participates in the regulation of systemic glucose homeostasis, where it negatively regulates insulin granule biogenesis in pancreatic islet beta cells (By similarity). Also regulates glucagon granule production in pancreatic alpha cells (By similarity). Inhibits nuclear translocation of the transcriptional coregulator PHB2 and may enhance estrogen receptor alpha (ESR1) transcriptional activity in breast cancer cells (PubMed:19496786). {ECO:0000250|UniProtKB:Q3UGY8, ECO:0000269|PubMed:19496786}. This is the function of ARFGEF3 (ARFGEF family member 3, Ensembl gene identifier ENSG00000112379).