The GBP1 gene consists of 11 exons (ranging from 102 to 1164 bp) and 10 introns. The coding sequence starts in the second exon.

Only one variant mRNA has been described for GBP-1 (Accession Number: NM_002053). This mRNA is 3050 bp long with a coding sequence of 1779 bp. Four polymorphisms have been described for GBP-1: c.232A>G (codon 78 Ile>Val), c.498G>C (codon 166 Glu>Asp), c.1046C>G (codon 349 Thr>Ser), c.1226C>G (codon 409 Ala>Gly).

A pseudogene has been identified for GBP1 (LOC400759 alias FLJ17004) on chromosome 1 (1p22.2, chro 1: 89645826-89663081, according to hg18-Mar_2006). Two pseudogenes have also been described in the mouse (pseudomGbp1 and pseudomGbp2).

GBP-1 belongs to the class of large GTPases that contains, in addition to the GBPs, three further groups of proteins, which share structural and biochemical properties: the dynamins, the Mx proteins and the atlastins. GBP-1 has a molecular weight of 67 kDa and its crystal structure has revealed the presence of two domains: (1) a N-terminal globular alpha/beta domain harbouring the GTPase activity and (2) a long C-terminal part organized in an index finger-like domain composed exclusively of seven alpha-helices (alpha7 - alpha13). The domains are connected by a short intermediate region consisting of one alpha-helix and a short two-stranded beta-sheet. In addition, GBP-1 harbours a C-terminal CAAX isoprenylation motif. GTPases typically harbour three classical GTP-binding domains: the phosphate-binding P-loop GXXXXGK(S/T), the phosphate- and Mg²⁺-binding DXXG motif (G, glycine; K, lysine; S, serine; D, aspartic acid; T, threonine; and X, any amino acid) and the guanine nucleotide-specificity providing (N/T)KXD motif (N, asparagine). In GBP-1 the classical (N/T)KXD motif is substituted by a conserved arginine-aspartic acid (RD)-motif (TLRD, with L, leucine and R, arginine).

GBP-1 was initially shown to be among the most highly induced proteins in human fibroblasts exposed to interferon (IFN)-gamma. Subsequently, it was reported that in vitro hGBP-1 expression can be induced by IFN-gamma in many different cell types including endothelial cells, fibroblasts, keratinocytes, B-cells, T-cells or peripheral blood mononuclear cells. In vivo expression of hGBP-1 has been predominantly detected in inflammatory tissues and has been found to be associated almost exclusively with endothelial cells and monocytes. It has been shown subsequently that hGBP-1 expression in endothelial cells is also induced by other pro-inflammatory cytokines such as IFNalpha, TNFalpha and IL1alpha/IL1beta. Many other cytokines (IL-4, IL-6, IL-10, IL-18), chemokines (MCP-1, PF4) or growth factors (angiopoietin-2, PDGF B/B) tested did not affect GBP-1 expression in these cells. Interestingly, the two major angiogenic growth factors (AGF: bFGF, VEGF) are able to inhibit the expression of GBP-1 induced by inflammatory cytokines.

The localization of GBP-1 is primarily cytosolic and its distribution is granular. Plasma membrane association at the level of tight junctions has also been described. In addition, GBP-1 has been shown to be secreted from IFN-gamma-stimulated endothelial cells through a non-classical secretion pathway.

GTPase activity
GBP-1 can bind the three nucleotides GTP, GDP and GMP with a relative low affinity (Kd mant-GMP=0,53 μM, Kd mant-GDP=2,4 μM, Kdmant-GppNHp=1,1 μM). GBP-1 has however the ability to hydrolyse GTP to both GDP and GMP with a high hydrolysis rate (max 95 min^-1). At physiological temperature GMP is the major product (90%) of hGBP1. On the contrary to small GTPases like Ras, GBP-1 does not require the presence of GEF (GTP exchange factor) or GAP (GTPase activating protein) proteins for its GTPase activity. In the case of GBP-1, the GTP hydrolysis is self-stimulated by oligomerization of the protein.
GBP-1 is involved in IFN-gamma response, either in infection or in inflammation.

The human GBP family comprises 7 highly homologous members, all located on the chromosome 1. GBP-1 is to 77% similar to GBP-2, 88% to GBP-3, 56% to GBP-4, 68% to GBP-5, 54% to GBP-6 and 56% to GBP-7. Homologues have been found in various species like zebrafish, chimpanzee (99% homology), rat, dog or mouse. GBP-1 shares 59% of homology with murine GBP-1 and murine GBP-2.

No somatic or germline mutations have yet been reported for human GBP-1.