Under selection pressure from pathogens, variable NK cell receptors that recognize polymorphic MHC class I evolved convergently in different species of placental @entity1 . Unexpectedly, diversified killer cell Ig-like receptors (KIRs) are shared by simian primates, including @entity1 , and @entity291 , but not by other species. Whereas much is known of @entity1 @entity9371 genetics and genomics, knowledge of @entity291 @entity9371 is limited to nine cDNA sequences. To facilitate comparison of the @entity291 and @entity1 @entity9371 gene families, we determined the genomic location, structure, and sequence of two @entity291 @entity9371 haplotypes and defined @entity9371 sequences of @entity23848 , the extinct wild ancestor of @entity291 . Larger than its @entity1 counterpart, the @entity291 @entity9371 locus evolved through successive duplications of a block containing ancestral KIR3DL and KIR3DX genes that existed before placental mammals. Comparison of two @entity291 @entity9371 haplotypes and @entity23848 @entity9371 show the @entity9371 are polymorphic and the gene organization and content appear conserved. Of 18 genes, 8 are functional and 10 were inactivated by point mutation. Selective inactivation of KIR3DL and activating receptor genes leaves a functional cohort of one inhibitory KIR3DL, one activating KIR3DX, and six inhibitory KIR3DX. Functional @entity9371 diversity evolved from KIR3DX in @entity291 and from KIR3DL in simian primates. Although independently evolved, @entity291 and @entity1 @entity9371 gene families share important function-related properties, indicating that @entity291 @entity9371 are NK cell receptors for @entity291 MHC class I. Combinations of @entity9371 and MHC class I are the major genetic factors associated with @entity1 disease and merit investigation in @entity291 .

Definition of the XXXX killer cell Ig-like receptor gene family: comparison with @entity23848 and @entity1 counterparts.

@entity1 :: ('9606', 'Species') :: ['humans', 'human', 'mammal'] @entity9371 :: ('3805', 'Gene') :: ['KIR'] @entity291 :: ('9913', 'Species') :: ['cattle', 'domestic cattle'] @entity23848 :: ('9909', 'Species') :: ['aurochs']
@entity291 :: (9913,Species) :: ['cattle']
