Phylogeny of Tamm-Horsfall protein.

The Tamm-Horsfall protein (THP, uromodulin) is urine's most abundant protein. The phylogenetic distribution of the gene for THP was examined in all the major vertebrate classes. Genomic DNA was obtaind from each vertebrate class and hybridized with a rat THP cDNA probe in a DNA hybridization assay. In separate experiments, a polymerase chain reaction assay was used to amplify segments of the THP gene using primers from a consensus sequence for THP among multiple mammalian species. Both methods revealed that the THP gene was present in all the vertebrate classes. These data demonstrate the evolutionary conservation of the THP gene among vertebrates and suggest a role for this protein that is common to the kidney of all vertebrates.