title: Non-excitable fluorescent protein orthologs found in ctenophores.
abstract: BACKGROUND
  Fluorescent proteins are optically active proteins found across many clades in metazoans. A fluorescent protein was recently identified in a ctenophore, but this has been suggested to derive from a cnidarian, raising again the question of origins of this group of proteins.
  
  
  RESULTS
  Through analysis of transcriptome data from 30 ctenophores, we identified a member of an orthologous group of proteins similar to fluorescent proteins in each of them, as well as in the genome of Mnemiopsis leidyi. These orthologs lack canonical residues involved in chromophore formation, suggesting another function.
  
  
  CONCLUSIONS
  The phylogenetic position of the ctenophore protein family among fluorescent proteins suggests that this gene was present in the common ancestor of all ctenophores and that the fluorescent protein previously found in a ctenophore actually derives from a siphonophore.
authors: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., 95039, Moss Landing, USA.|Present address: Ludwig-Maximilians-Universität München, Munich, Germany.
authors: Warren R
authors: WR
authors: Francis
authors: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., 95039, Moss Landing, USA.
authors: Lynne M
authors: LM
authors: Christianson
authors: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., 95039, Moss Landing, USA.
authors: Meghan L
authors: ML
authors: Powers
authors: National Human Genome Research Institute, National Institutes of Health, 50 South Drive, Bethesda, 20892, USA.|Present address: Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, Florida, 32080, USA.
authors: Christine E
authors: CE
authors: Schnitzler
authors: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., 95039, Moss Landing, USA. haddock@mbari.org.
authors: Steven H
authors: SH
authors: D Haddock
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D037302:Ctenophora / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D016678:Genome; D008164:Luminescent Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D010802:Phylogeny; D059467:Transcriptome
chemical_list: D008164:Luminescent Proteins
keywords: Ctenophore; Fluorescence; Fluorescent protein; Haeckelia; Siphonophore; Transcriptome