ODORANT-BINDING PROTEINS

Odorant-binding proteins (OBPs) are low-molecular-weight soluble prote ins highly concentrated in the nasal mucus of vertebrates and in the s ensillar lymph of insects. Their affinity toward odors and pheromones suggests a role in olfactory perception, but their physiological funct ion has not been clearly defined. Several members of this class of pro teins have been isolated and characterized both in insects and vertebr ates; in most species two or three types of OBPs are expressed in the nasal area. Vertebrates OBPs show significant sequence similarity with a superfamily of soluble carrier proteins called lipocalins. They inc lude some proteins of particular interest that are thought to be invol ved in the mechanism of releasing and modulating chemical messages wit h pheromonal activity. The data on vertebrate OBPs are here reviewed t ogether with the most relevant information on related proteins. Theori es and models of the physiological functions of odorant-binding protei ns are presented and discussed.