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

Short name: G_GB1_RHD3_dom

Overlapping homologous superfamilies

Domain relationships



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 and an 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. One conserved subfamily is typified by the Arabidopsis protein root hair defective 3 (RHD3), whose othologs are present in all crown group eukaryotes. The other subfamily 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 an N-terminal RING finger domain, which implicates these proteins in ubiquitin-mediated signaling. Most members of this family have a large C-terminal, alpha-helical extension that probably participates in protein-protein interactions. The GB1/RHD3-type G domain has a low intrinsic affinity for nucleotide and often depends on nucleotide-dependent homodimerization to facilitate GTP hydrolysis [PMID: 11916378, PMID: 10676968, PMID: 10970849, PMID: 16511497, PMID: 22082223, PMID: 21220294].

The large GB1/RHD3-type G domain consists of a six-stranded beta-sheet surrounded by eight helices. It contains the conserved sequence elements of GTP-binding proteins with modifications [PMID: 10676968, PMID: 16511497, PMID: 21220294].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005525 GTP binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles