Characteristics of Ligand Binding and Release by Major Urinary Proteins

Abstract

The Major Urinary Proteins (MUPs) are abundant in the urine of house mice (Finlayson and Baumann 1958). They have a characteristic eight-stranded β-barrel structure, which incorporates a central, hydrophobic pocket or calyx (Böcskei et al., 1992; Zidek et al., 1999 a, b). This distinctive structure is common to a number of other proteins, collectively called the Lipocalin Superfamily (Flower et al., 1993). The central hydrophobic pocket of the lipocalins allows the binding and transport of hydrophobic ligands in aqueous solutions (Flower 1994). When found in urine, MUPs are associated with a number of endogenous ligands (Bacchini et al., 1992; Robertson et al., 1993; Novotny et al., 1999 a, b). A number of these compounds including, brevicomin (3,4-dehydro-exo-brevicomin) and thiazole (2-sec-butyl-4,5-dihydrothiazole) are primer pheromones, which exhibit a variety of behavioural and physiological effects (Jemiolo et al., 1985, Jemiolo et al., 1986). The association of MUPs with these pheromones and their abundant presence in urine has led to the suggestion that MUPs play an important role in olfactory communication.