Functional Aspects of b-Lactoglobulin, Major Urinary Protein and Odorant-Binding Protein
Andrea Cavaggioni, Paolo Pelosi, Stephen G. Edwards and Lindsay Sawyer
The lipocalin family contains more than 30 distinct proteins that are widely distributed throughout the living world. However, the exact physiological functions of many members of the family are unknown although several are inferred by analogy. Three of the core lipocalins, b-lactoglobulin, major urinary protein and odorant binding protein are found in three significant mammalian secretions, milk, urine and nasal mucous, respectively. Their physiological functions are discussed in the light of the available evidence. It is proposed that b-lactoglobulin is principally a nutritional protein that is closely related to glycodelin, a protein with several reported functions, including immuno-modulation. Mouse major urinary protein with its close relative, rat a2u-globulin, and aphrodisin are involved in signalling amongst members of the same species. Odorant binding proteins are also signalling proteins involved in the detection of odours in the nose.