title: The evolution of the class A scavenger receptors.
abstract: BACKGROUND
  The class A scavenger receptors are a subclass of a diverse family of proteins defined based on their ability to bind modified lipoproteins. The 5 members of this family are strikingly variable in their protein structure and function, raising the question as to whether it is appropriate to group them as a family based on their ligand binding abilities.
  
  
  RESULTS
  To investigate these relationships, we defined the domain architecture of each of the 5 members followed by collecting and annotating class A scavenger receptor mRNA and amino acid sequences from publicly available databases. Phylogenetic analyses, sequence alignments, and permutation tests revealed a common evolutionary ancestry of these proteins, indicating that they form a protein family. We postulate that 4 distinct gene duplication events and subsequent domain fusions, internal repeats, and deletions are responsible for the diverse protein structures and functions of this family. Despite variation in domain structure, there are highly conserved regions across all 5 members, indicating the possibility that these regions may represent key conserved functional motifs.
  
  
  CONCLUSIONS
  We have shown with significant evidence that the 5 members of the class A scavenger receptors form a protein family. We have indicated that these receptors have a common origin which may provide insight into future functional work with these proteins.
authors.affiliation: Department of Pathology and Molecular Medicine, McMaster University, 1200 Main Street West, Hamilton, L8N 3Z5 Ontario, Canada.
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Whelan
authors.forename: Conor J
authors.initials: CJ
authors.lastname: Meehan
authors.forename: G Brian
authors.initials: GB
authors.lastname: Golding
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: McConkey
authors.forename: Dawn M E
authors.initials: DM
authors.lastname: Bowdish
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D030541:Databases, Genetic; D019143:Evolution, Molecular; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D009893:Opossums; D010802:Phylogeny; D051117:Scavenger Receptors, Class A / Q000145:classification / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D051117:Scavenger Receptors, Class A