G protein alpha subunit multigene family in the Japanese puffer fish Fugu rubripes: PCR from a compact vertebrate genome.

Abstract

We compare the complexity and organization of the G protein c~ subunit multigene family in the vertebrate genomes of mammals and the Japanese puffer fish Fugu rubripes. Fourteen Fugu G~ genes were identified of the 16 genes characterized previously in mammals, including Fugu genes from the four classes of alpha subunits Gs, Gi, Gq, and G12. Fugu and mammalian GoL coding sequences are highly homologous, and the intron/exon structure of the fish and mammalian orthologs is identical throughout the coding regions. A novel GoL gene, Gc~pl, was also identified in Fugu rubripes and two other species of puffer fish. The complete sequence of Gnaz and the tandemly duplicated genes Gnai2 and Gnarl were obtained from a Fugu genomic cosmid library.introns in the puffer fish GoL genes lacked repeat DNA sequences, other than simple sequence length repeats, and most introns were significantly shorter in Fugu than in mammalian orthologs. The compact genome of puffer fish provides a unique vertebrate model for characterizing multigene families and identifying novel genes directly from genomic DNA by PCR amplification with degenerate primers. The fact that Fugu encodes most, if not all, of the G protein alpha subunits identified in mammals strongly supports Fugu as a model organism for vertebrate genome research.

Enteroendocrine profile of α-transducin immunoreactive cells in the gastrointestinal tract of the European sea bass (Dicentrarchus labrax)

“…Recent studies on the fish genome failed to detect a gene encoding an ortholog of the mammalian G αgust gene (Ohmoto et al, 2011), however, Oka and Korsching (2011) showed 80% homology between G αgust and other G proteins, and Sarwal et al (1996) reported a high homology of Gα gene between mammals and the puffer fish Fugu rubripes , with an identical intron/exon structure throughout the coding regions. Several lines of evidence support the tissue specificity of the G αtran and G αgust antibodies used in our study, including Western blot and immunoblocking experiments.…”

G proteins, chemosensory perception, and the C. elegans genome project: An attractive story

“…What mechanisms of gene duplication facilitated the accumulation of so many divergent G␣ genes? In contrast to six pairs of tandemly duplicated G␣ genes found in humans, mice, and Fugu, (13,14) the G␣, ␤, and ␥ genes in C. elegans genes are dispersed throughout the genome. Some G␣ genes in C. elegans cluster on chromosomes I and V but they are not closely related, either by sequence or gene structure, which obfuscates the gene duplication mechanism.…”

Fugu: a compact vertebrate reference genome

“…Although Fugu appears to have a duplicate copy of one of the Hox clusters [8], there is no evidence for large scale duplication in the genome. Extensive searches for members of multigene families in the Fugu by polymerase chain reaction screening and library probing have not identified significant numbers of either duplicated genes or pseudogenes [9–14]. Although nine actin genes were identified in the Fugu as compared to six known so far in mammals, one of the new actin genes in the Fugu is the result of a tandem duplication and another new gene has a unique exon–intron structure suggesting that they are not the result of genome duplication [11].…”