title: Extensive duplications of phototransduction genes in early vertebrate evolution correlate with block (chromosome) duplications.
abstract: Many gene families in mammals have members that are expressed more or less uniquely in the retina or differentially in specific retinal cell types. We describe here analyses of nine such gene families with regard to phylogenetic relationships and chromosomal location. The families are opsins, G proteins (alpha, beta, and gamma subunits), phosphodiesterases type 6, cyclic nucleotide-gated channels, G-protein-coupled receptor kinases, arrestins, and recoverins. The results suggest that multiple new gene copies arose in all of these families very early in vertebrate evolution during a period with extensive gene duplications. Many of the new genes arose through duplications of large chromosome regions (blocks of genes) or even entire chromosomes, as shown by linkage with other gene families. Some of the phototransduction families belong to the same duplicated regions and were thus duplicated simultaneously. We conclude that gene duplications in early vertebrate evolution probably helped facilitate the specialization of the retina and the subspecialization of different retinal cell types.
authors.affiliation: Department of Neuroscience, Unit of Pharmacology, Uppsala University, Box 593, SE-751 24 Uppsala, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Nordström
authors.forename: Tomas A
authors.initials: TA
authors.lastname: Larsson
authors.forename: Dan
authors.initials: D
authors.lastname: Larhammar
mesh_terms: D000818:Animals; D019393:Arrestin / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000235:genetics; D002875:Chromosomes / Q000235:genetics*; D054815:Cyclic Nucleotide-Gated Cation Channels; D019143:Evolution, Molecular; D005136:Eye Proteins / Q000235:genetics; D051606:G-Protein-Coupled Receptor Kinase 1; D020440:Gene Duplication; D020131:Genes, Duplicate / Q000235:genetics*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics; D006801:Humans; D007473:Ion Channels / Q000235:genetics; D008074:Lipoproteins / Q000235:genetics; D010727:Phosphoric Diester Hydrolases / Q000235:genetics; D010802:Phylogeny; D011494:Protein Kinases / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics; D051603:Recoverin; D017299:Rod Opsins / Q000235:genetics; D015293:Transducin / Q000235:genetics; D014714:Vertebrates / Q000235:genetics*; D014785:Vision, Ocular / Q000235:genetics*
chemical_list: D019393:Arrestin; D002135:Calcium-Binding Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D005136:Eye Proteins; D007473:Ion Channels; D008074:Lipoproteins; D021122:Protein Subunits; C496731:RCVRN protein, human; D017299:Rod Opsins; D051603:Recoverin; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1; C496764:GRK1 protein, human; D010727:Phosphoric Diester Hydrolases; D020962:Heterotrimeric GTP-Binding Proteins; D015293:Transducin