title: Identification and characterization of the fibrinogen-like domain of fibrinogen-related proteins in the mosquito, Anopheles gambiae, and the fruitfly, Drosophila melanogaster, genomes.
abstract: BACKGROUND
  The fibrinogen-like (FBG) domain, which consists of approximately 200 amino acid residues, has high sequence similarity to the C-terminal halves of fibrinogen beta and gamma chains. Fibrinogen-related proteins (FREPs), which contain FBG domains in their C-terminal region, are found universally in vertebrates and invertebrates. In invertebrates, FREPs are involved in immune responses and other aspects of physiology. To understand the complexity of this family in insects, we analyzed FREPs in the mosquito genome and made comparisons to FREPs in the fruitfly genome.
  
  
  RESULTS
  By using the genome data of the mosquito, Anopheles gambiae, 53 FREPs were identified, whereas only 20 members were found in the Drosophila melanogaster genome. Using sequence profile analysis, we found that FBG domains have high sequence similarity and are highly conserved throughout the FBG domain region. By secondary structure analysis and comparison, the FBG domains of FREPs are predicted to function in recognition of carbohydrates and their derivatives on the surface of microorganisms in innate immunity.
  
  
  CONCLUSIONS
  Detailed sequence and structural analysis discloses that the FREP family contains FBG domains that have high sequence similarity in the A. gambiae genome. Expansion of the FREP family in mosquitoes during evolutionary history is mainly accounted for by a major expansion of the FBG domain architecture. The characterization of the FBG domains in the FREP family is likely to aid in the experimental analysis of the ability of mosquitoes to recognize parasites in innate immunity and physiologies associated with blood feeding.
authors.affiliation: Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA. xwang@svm.vetmed.wisc.edu
authors.forename: Xinguo
authors.initials: X
authors.lastname: Wang
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhao
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Christensen
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005340:Fibrinogen / Q000737:chemistry* / Q000235:genetics; D016678:Genome; D007113:Immunity, Innate; D008957:Models, Genetic; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D005340:Fibrinogen; D004247:DNA