Characterization of a caprine β-lactoglobulin pseudogene, identification and chromosomal localization by in situ hybridization in goat, sheep and cow

A β-lactoglobulin (β-LG) pseudogene has been isolated and sequenced (7634 bp) in goat. Its structure is remarkably similar to that of the β-LG gene with all seven exons placed in the same relative position. The pseudogene seems to have originated by gene duplication, but a non uniform distribution of similarities along the sequence suggests that events of gene conversion have also occurred during its evolution. The comparison of the predicted ancestral protein encoded by the pseudogene shows its evolutionary relationship to the monomeric β-LG II forms of the β-LG reported in some non-ruminant species. Southern-blot analysis shows that similar pseudogenes are also found in the genome of sheep and cow. The pseudogene has been mapped by fluorescent in situ hybridization (FISH) to sheep chromosome 3p28 and cattle and goat chromosomes 11q28, in the same mapped position as that found for the β-LG gene in all these species.