title: The origins of novel protein interactions during animal opsin evolution.
abstract: BACKGROUND
  Biologists are gaining an increased understanding of the genetic bases of phenotypic change during evolution. Nevertheless, the origins of phenotypes mediated by novel protein-protein interactions remain largely undocumented.
  
  
  RESULTS
  Here we analyze the evolution of opsin visual pigment proteins from the genomes of early branching animals, including a new class of opsins from Cnidaria. We combine these data with existing knowledge of the molecular basis of opsin function in a rigorous phylogenetic framework. We identify adaptive amino acid substitutions in duplicated opsin genes that correlate with a diversification of physiological pathways mediated by different protein-protein interactions.
  
  
  CONCLUSIONS
  This study documents how gene duplication events early in the history of animals followed by adaptive structural mutations increased organismal complexity by adding novel protein-protein interactions that underlie different physiological pathways. These pathways are central to vision and other photo-reactive phenotypes in most extant animals. Similar evolutionary processes may have been at work in generating other metazoan sensory systems and other physiological processes mediated by signal transduction.
authors.affiliation: Ecology, Evolution and Marine Biology, University of California at Santa Barbara, Santa Barbara, California, United States of America.
authors.forename: David C
authors.initials: DC
authors.lastname: Plachetzki
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Degnan
authors.forename: Todd H
authors.initials: TH
authors.lastname: Oakley
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000378:metabolism; D019143:Evolution, Molecular; D017403:In Situ Hybridization; D008027:Light; D016013:Likelihood Functions; D008390:Markov Chains; D008954:Models, Biological; D010641:Phenotype; D010802:Phylogeny; D025941:Protein Interaction Mapping; D017299:Rod Opsins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D013045:Species Specificity
chemical_list: D017299:Rod Opsins