ARHGEF16 is a guanyl-nucleotide exchange factor (GEF) for the small GTPase RHOG. It stimulates the exchange of RHOG-associated GDP for GTP, switching the GTPase into its active state. The protein may also contribute to chemotactic cell migration by mediating the activation of RAC1 by EPHA2, and it may activate CDC42, including in the activation of CDC42 by the viral protein HPV16 E6.

The ARHGEF16 protein is found in the cytoplasm. HGNC places the gene in several groups: pleckstrin homology domain containing, Dbl family Rho GEFs and SH3 domain containing. These groupings fit its role as a Rho GEF and point to domains that commonly mediate protein-protein and protein-lipid interactions. NCBI Gene notes that the specific function of the protein is not fully defined, but that it is thought to be involved in such interactions. A mouse ortholog, Arhgef16, is annotated.

The ARHGEF16 gene has also been listed under the symbol NBR, and the protein under the name Rho guanine nucleotide exchange factor (GEF) 16, with GEF16 as an alias. Researchers studying Rho family signalling, cell migration and GTPase regulation may also look at related exchange factors such as ARHGEF1, ARHGEF2, ARHGEF7, ARHGEF10 and ARHGEF12.