ARHGDIG belongs to the Rho GDI family, whose members act as GDP-dissociation inhibitors (GDIs). GDIs play a primary role in modulating the activation of GTPases by inhibiting the exchange of GDP for GTP. In this way they help to hold Rho-type GTPases in a restrained state.

According to UniProt, ARHGDIG inhibits the GDP/GTP exchange reaction of RhoB. It interacts specifically with the GDP-bound and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show growth-regulated expression in mammalian cells. The protein stimulates the release of GDP-bound RhoB but not of GTP-bound RhoB. It also shows less ability to inhibit the dissociation of prebound GTP, so its effect is greatest on the exchange step rather than on GTP release.

The human ARHGDIG gene encodes a cytoplasmic protein, and the Rho GDI family is the gene group assigned by HGNC. The gene was previously named Rho GDP dissociation inhibitor (GDI) gamma, and the protein is also called RHOGDI-3. A mouse ortholog, Arhgdig, is recorded. The NCBI Gene summary points to the related family member ARHGDIB for further context on GDI function. Researchers studying Rho GTPase regulation may use ARHGDIG as a reference point when comparing GDI family members.