Ligand binding characteristics of homologous rat and mouse urinary proteins and pyrazine-binding protein of calf.

1. The binding affinities of three classes of homologous proteins, alpha 2u protein from rat urine, major urinary protein of mouse and pyrazine-binding protein of calf nasal mucosa have been determined for a panel of ligands. 2. Best ligands were low threshold odorants for man, but chemically unrelated. 3. The binding spectra of the homologous proteins were different.