Protein Domain : GB1/RHD3-type guanine nucleotide-binding (G) domain IPR030386

Type	Domain
Description	The P-loop guanosine triphosphatases (GTPases) control a multitude of biological processes, ranging from cell division, cell cycling,and signal transduction, to ribosome assembly and protein synthesis. GTPases exert their control by interchanging between an inactive GDP-bound state andan active GTP-bound state, thereby acting as molecular switches. The common denominator of GTPases is the highly conserved guanine nucleotide-binding (G)domain that is responsible for binding and hydrolysis of guanine nucleotides. The GB1/RHD3 GTPase family contains a large G domain (~230 amino acids). It is widespread in eukaryotes, but not detectable in bacteria or archaea. Oneconserved subfamily is typified by the Arabidopsis protein root hair defective 3 (RHD3), whose othologs are present in all crown group eukaryotes. The othersubfamily is typified by the interferon gamma-induced antiviral GB1 protein that is conserved in animals. The other GTPases of this subfamily are the brain finger proteins (BFPs), in which the GTPase domain is combined with anN-terminal RING finger domain, which implicates these proteins in ubiquitin-mediated signaling. Most members of this family have alarge C-terminal, α-helical extension that probably participates in protein-protein interactions. The GB1/RHD3-type G domain has a low intrinsicaffinity for nucleotide and often depends on nucleotide-dependent homodimerization to facilitate GTP hydrolysis [, , , , , ].The large GB1/RHD3-type G domain consists of a six-stranded β-sheet surrounded by eight helices. It contains the conservedsequence elements of GTP-binding proteins with modifications [ , , ].
Short Name	G_GB1_RHD3_dom