Control is exerted by GTPases, which act as molecular switches by converting between an inactive GDP-bound state and an active GTP-bound state. The G domain of GTPases is highly conserved and is responsible for binding and hydrolyzing guanine nucleotides. Large G domains of the GB1/RHD3 type are present in the IPR030386 family of GB1/RHD3 GTPases, and these G domains share certain conserved sequence elements with modified GTP-binding proteins. Root hair defect 3 (RHD3) is a protein found in Arabidopsis thaliana that represents a conserved subfamily with its homologue present in all crown group eukaryotes. The GB1 protein, an antiviral protein induced by interferon gamma and found in all animals, is a member of a different subfamily. tr-type G domain conserved site (IPR031157). Hydrolysis of GTP to GDP has been shown to change the shape of proteins, and this residue is found in a region with serine and threonine.