Genomic positioning and phylogenetic relationship of mouse Irg GTPases. (a) Disposition of the 23 Irg genes on the mouse karyotype. Individual Irg genes are listed in correct gene order in each cluster. (b) Positioning and orientation of Irg genes in the mouse chromosome 11 and 18 clusters. Positions of genes refer to the location in Mouse ENSEMBL release (v28.33d.1, February 2005)  of the first G of the glycine codon of the G1 motif (GKS or GMS) of the GTP-binding domain of each gene. The segments of the chromosome 11 cluster indicated with square brackets are regions of uncertain structure. Gene orientation is given by black arrows. The shaded region of the chromosome 11 map is a duplication introduced in Mouse ENSEMBL v28.33d.1 (February 2005) in an attempt to resolve a region of high ambiguity indicated by the longer square bracket. In our view this duplication does not resolve the ambiguities consistently, and we see no justification at present for the duplicated Irgb5 and Irgb6 genes. The sibling genes Irgb3 and Irgb4 differ by only nine nucleotides; in this case, however, the independent existence of the two genes is proved by the proximity of the PA28βψ retropositioned pseudo-gene to Irgb3 but not to Irgb4, in addition to consistent sequence differences. We have left the duplication of the Irgb5/Irgb6 region in the map for consistency of the base numbering with this release of ENSEMBL. *Indicates minor sequence differences presumably due to sequencing errors. (c) Unrooted tree (p-distance based on neighbour-joining method) of nucleotide sequences of the G-domains of the 23 mouse Irg GTPases, including the two presumed pseudo-genes Irga5 and Irgb7. The sources of all Irg sequences are given in Additional data file 1, and the nucleotide and amino acid sequences themselves are collected in the p47 (IRG) GTPase database from our laboratory website . (d) Phylogenetic tree of the amino acid sequences of the G-domains of 21 mouse Irg GTPases rooted on the G-domain of H-Ras-1 (accession number: P01112). The products of the two presumed pseudo-genes Irga5 and Irgb7 are excluded from the analysis.
Bekpen et al. Genome Biology 2005 6:R92 doi:10.1186/gb-2005-6-11-r92