title: RPS4Y gene family evolution in primates.
abstract: BACKGROUND
  The RPS4 gene codifies for ribosomal protein S4, a very well-conserved protein present in all kingdoms. In primates, RPS4 is codified by two functional genes located on both sex chromosomes: the RPS4X and RPS4Y genes. In humans, RPS4Y is duplicated and the Y chromosome therefore carries a third functional paralog: RPS4Y2, which presents a testis-specific expression pattern.
  
  
  RESULTS
  DNA sequence analysis of the intronic and cDNA regions of RPS4Y genes from species covering the entire primate phylogeny showed that the duplication event leading to the second Y-linked copy occurred after the divergence of New World monkeys, about 35 million years ago. Maximum likelihood analyses of the synonymous and non-synonymous substitutions revealed that positive selection was acting on RPS4Y2 gene in the human lineage, which represents the first evidence of positive selection on a ribosomal protein gene. Putative positive amino acid replacements affected the three domains of the protein: one of these changes is located in the KOW protein domain and affects the unique invariable position of this motif, and might thus have a dramatic effect on the protein function.
  
  
  CONCLUSIONS
  Here, we shed new light on the evolutionary history of RPS4Y gene family, especially on that of RPS4Y2. The results point that the RPS4Y1 gene might be maintained to compensate gene dosage between sexes, while RPS4Y2 might have acquired a new function, at least in the lineage leading to humans.
authors.affiliation: Genètica de Conservació Animal, Institut de Recerca i Tecnologia Agroalimentàries, Crta, de Cabrils km2, 08348 Cabrils, Spain. olga.andres@gmail.com
authors.forename: Olga
authors.initials: O
authors.lastname: Andrés
authors.forename: Thomas
authors.initials: T
authors.lastname: Kellermann
authors.forename: Francesc
authors.initials: F
authors.lastname: López-Giráldez
authors.forename: Julio
authors.initials: J
authors.lastname: Rozas
authors.forename: Xavier
authors.initials: X
authors.lastname: Domingo-Roura
authors.forename: Montserrat
authors.initials: M
authors.lastname: Bosch
mesh_terms: D000818:Animals; D018076:DNA, Complementary; D019143:Evolution, Molecular; D005260:Female; D020440:Gene Duplication; D006801:Humans; D007438:Introns; D008297:Male; D008957:Models, Genetic; D005810:Multigene Family; D010802:Phylogeny; D011323:Primates / Q000145:classification / Q000235:genetics*; D012269:Ribosomal Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D012269:Ribosomal Proteins; C031798:ribosomal protein S4