Guanine nucleotide exchange factor for ARF6 (By similarity). Isoform 2 and isoform 3 induce cytoskeletal remodeling, but lead to distinct morphological changes in HeLa cells: isoform 2 induces cell elongation and formation of actin-rich protrusions, whereas isoform 3 promotes the formation of membrane ruffles and loss of stress fibers (PubMed:19494129). Interacts with ACTN1 (PubMed:17298598). Interacts (ARF6-bound form) with KCNK1; does not interact with KCNK1 in the absence of ARF6 (PubMed:15540117). Colocalizes with ACTN1 in membrane ruffles and central reticular structures. Accumulates in microvilli-like protrusions. Colocalizes with F-actin in membrane ruffles. Distributed uniformly on the plasma membrane, as well as throughout the cytoplasm during metaphase. Subsequently concentrated at patches in the equatorial region at the onset of cytokinesis, and becomes distributed in the equatorial region concurrent with cleavage furrow ingression. In later cytokinesis phases, fades away from the cleavage furrow and becomes uniformly distributed throughout the plasma membrane. Highest expression detected in brain and some expression detected also in uterus, stomach, ovary and intestine, with isoform 2 being expressed at the highest levels. In the brain, isoform 1 is highly expressed in the strata oriens, radiatum, lacunosum-moleculare of the hippocampal CA1-3 regions and the dentate molecular layer of the hippocampal formation, with lower levels detected in the neuronal cell layers and the stratum lucidum (at protein level). Not detected in tongue, thymus, spleen, lung, heart, liver and kidney. Expressed in embryonic, early postnatal and adult brain, with expression up-regulated at postnatal day 4-8 and down-regulated in adults. Isoform 2 expression is up-regulated in adults. Produced by alternative promoter usage. Produced by alternative splicing of isoform 1. Belongs to the PSD family.