Species-specific evolution of immune receptor tyrosine based activation motif-containing @entity70766 -related immune receptors in the XXXX .

@entity1 @entity70766 @entity19 @entity235 @entity10580 @entity70767
BACKGROUND: Although the impact of pathogens on the evolution of the @entity1 immune system is still under debate, proteins, which both regulate immune responses and serve as cellular receptors for pathogens should be at the forefront of pathogen-driven host evolution. The @entity10580 ( @entity10580 ) gene family codes for such proteins and indeed shows tremendous species-specific variation between @entity1 and rodents. Since little is known about the @entity10580 gene family in other lineages of placental mammals, we expected to gain new insights into the evolution of the rapidly diverging @entity10580 family by analyzing the @entity10580 family of the @entity235 . RESULTS: Here we describe the complete @entity10580 gene family in the @entity235 . We found that the gene coding for the ITIM-bearing immunoregulatory molecule @entity70766 gave rise to a recent expansion of the @entity235 @entity10580 gene family by gene duplication, similar to that previously found in @entity1 and @entity19 . However, while the @entity19 and @entity1 CEACAMs ( @entity10580 -related cell adhesion molecules) are predominantly secreted and GPI-anchored, respectively, in the @entity235 , most of the CEACAMs represent ITAM-bearing transmembrane proteins. One of these proteins, @entity70767 , exhibits nearly complete sequence identity with the ligand-binding N domain of @entity70766 , but antagonizing signaling motifs in the cytoplasmic tail. Comparison of nonsynonymous and synonymous substitutions indicates that the @entity70767 N domain is under the strongest purifying selection of all @entity235 @entity70766 -related CEACAMs. In addition, @entity70767 shows a similar expression pattern in resting immune cells and tissues as @entity70766 . However, upon activation @entity70767 mRNA and @entity70766 mRNA are differentially regulated. CONCLUSION: Thus, @entity70766 and @entity70767 are the first paired immune receptors identified within the @entity10580 gene family, which are expressed on T cells and are most likely involved in the fine-tuning of T cell responses. The direction of gene conversion accompanied by purifying selection and expression in immune cells suggests the possibility that @entity70767 evolved in response to selective pressure imposed by species-specific pathogens.
