Membrane receptor for odour-binding proteins.
Specific binding of 125I-labelled bovine odour-binding protein (OBP) to isolated membranes from nasal mucosa was demonstrated. The interaction reached equilibrium within 30 min at 37 degrees C and was reversible. A Scatchard analysis of the equilibrium binding revealed a single population of binding sites, with the calculated equilibrium dissociation constant and maximum number of binding sites being 2.25 +/- 0.5 microM and 18.5 +/- 2 pmol/mg of membrane protein respectively (n = 2). Receptor activity was decreased on digestion by trypsin, proteinase K or endoglycosidase H, was heat labile and was sensitive to thiol-group-specific reagents. With the exception of rat and mouse major urinary proteins, which exhibit a high degree of structural similarity with OBP and bind similar ligands, other members of the lipocalin family, such as retinol-binding protein and beta-lactoglobulin, failed to inhibit the binding of 125I-labelled OBP to its receptor. The receptor seems not to be restricted to olfactory tissues, as it was detected in a variety of other tissues. This suggests that OBP is unlikely to play a role only in olfactory signal transduction. It might have a much broader role within the body; possibilities include a role in detoxification or signalling.
Boudjelal
M
M
Department of Biochemistry and Molecular Biology, University of Leeds. U.K.
Sivaprasadarao
A
A
Findlay
J B
JB
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D019286:Endopeptidase K; D004848:Epithelium / Q000378:metabolism; D007700:Kinetics; D007782:Lactoglobulins; D009297:Nasal Mucosa / Q000378:metabolism*; D009812:Odorants; D011719:Pyrazines / Q000378:metabolism; D018035:Receptors, Odorant / Q000302:isolation & purification / Q000378:metabolism*; D012177:Retinol-Binding Proteins; D012697:Serine Endopeptidases / Q000494:pharmacology; D012903:Smell / Q000502:physiology*; D013696:Temperature; D014357:Trypsin / Q000494:pharmacology
D007782:Lactoglobulins; D011719:Pyrazines; D018035:Receptors, Odorant; D012177:Retinol-Binding Proteins; C045648:odorant-binding protein; D012697:Serine Endopeptidases; D014357:Trypsin; D019286:Endopeptidase K; C034376:2-isobutyl-3-methoxypyrazine