Odour binding protein

Table 3.1 Odourant Binding Proteins N-terminai sequences of various mammalian urinary and nasal lipocalyins — correspondence/homology with pig salivary protein, pig-SAL (Id <60%) (from Pelosi, 1998).

Pelosi P. (1994). Odourant-binding proteins. Crit Rev Biochem Molec Biol 29, 199-228. 

Pelosi P. (1998). Odourant-binding proteins structural aspects. Ann NY Acad Sci 855, 333-348. 

Biessmann H., Walter M. F., Dimitratos S. and Woods D. (2002) Isolation of cDNA clones encoding putative odourant binding proteins from the antennae of the malaria-transmitting mosquito, Anopheles gambiae. Insect Mol. Biol. 11, 123-132. 

Christophides G. K., Mintzas A. C. and Komitopoulou K. (2000) Organization, evolution and expression of a multigene family encoding putative members of the odourant binding protein family in the medfly Ceratitis capitata. Insect Mol. Biol. 9, 185-195. 

Robertson H. M., Martos R., Sears C. R., Todres E. Z., Walden K. K. and Nardi J. B. (1999) Diversity of odourant binding proteins revealed by an expressed sequence tag project on male Manduca sexta moth antennae. Insect Mol. Biol. 8, 501-518. 

Thymianou S., Mavroidis M., Kokolakis G., Komitopoulos K., Zacharopoulou A. and Mintzas A. C. (1998) Cloning and characterization of a cDNA encoding a male-specific serum protein of the Mediterranean fruit fly, Ceratitis capitata, with sequence similarity to odourant binding proteins. Insect Mol. Biol. 7, 345-353. 

Odour-binding protein >oV Receptor proteins Ca2+ ion channel... 

Another possible mechanism is the transport of odorant molecules across the mucus by odour-binding proteins (OBPs). These proteins are known to be present in the mucus and are known to bind odorants. It is possible that the OBPs could deliver the odorants to the receptor proteins or that the receptor proteins actually bind to an OBP-odorant complex. The former is the more generally accepted hypothesis. In either case, it is possible that the OBPs are involved in recognition since there are distinct classes of OBP and their affinities for odorants and for different receptor proteins are expected to be different. 

Lipocalins are a family of proteins, which serve to transport small molecules around the body. A sub-set of the lipocalin family is found in the nasal mucosa and its members are known as odour-binding proteins (OBPs). These proteins are known to bind odorants but their role in olfaction is not understood at present. Each OBP is really a complex of two cup-shaped proteins with a hinge formed by the amino acid backbone of one passing through that of the other. Once they have bound a substrate, the cups come together at the rims and so form a spherical hydrophilic unit and an X-ray crystal structure of such an OBP odorant complex has been published (Bianchet et al., 1996). The role of the OBP could be to... 

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