This review discusses the anatomy of human odorant reception, with particul
ar reference to the seven-helical transmembrane-protein superfamily of olfa
ctory receptors, the concept of a novel multigene olfactory-receptor family
, the location of the olfactory-receptor genes in the human genome and the
characterization of the receptor proteins by cloning and overexpression. It
then turns to the evidence for secondary message transduction following od
orant binding, and the latest evidence on the structural analysis of G-prot
ein coupled signalling as well as how the binding of odorant molecules to t
he transmembrane olfactory receptors is transmitted through the neural path
ways to the brain, including the remarkable success in generating cDNA libr
aries from single neurons.