Adaptive Evolution of XXXX Peptide Receptors in Mammals.

@entity1 @entity5038 @entity535 @entity48093 @entity51758 @entity435
UNASSIGNED: The @entity435 peptide receptors (FPRs) are a family of chemoattractant receptors with important roles in host defense and the regulation of inflammatory reactions. In @entity1 , three FPR paralogs have been identified ( @entity5038 , @entity51758 , and @entity48093 ) and may have functionally diversified by gene duplication and adaptive evolution. However, the evolutionary mechanisms operating in the diversification of FPR family genes and the changes in selection pressures have not been characterized to date. Here, we have made a comprehensive evolutionary analysis of FPR genes from @entity1 species. Phylogenetic analysis showed that an early duplication was responsible for @entity5038 and @entity51758 / @entity48093 splitting, and @entity48093 originated from the latest duplication event near the origin of primates. Codon-based tests of positive selection reveal interesting patterns in @entity5038 and @entity51758 versus @entity48093 , with the first two genes showing clear evidence of positive selection at some sites while the majority of them evolve under strong negative selection. In contrast, our results suggest that the selective pressure may be relaxed in the @entity48093 lineage. Of the six @entity535 sites inferred to evolve under positive selection in @entity5038 and @entity51758 , four sites were located in extracellular loops of the protein. The electrostatic potential of the extracellular surface of FPR might be affected more frequently with @entity535 substitutions in positively selected sites. Thus, positive selection of FPRs among mammals may reflect a link between changes in the sequence and surface structure of the proteins and is likely to be important in the host's defense against invading pathogens.
