what kinds of molecules are involved in smell
1 The cilia of the sensory neurons are immersed in a layer of mucus. 2  Odorant molecules (molecules that we can smell) dissolve in the mucus and. 3  bind to receptors on the cilia.4  These are 7-pass transmembrane proteins. 5  Binding of the odorant activates a G protein coupled to the receptor on its cytoplasmic side. bind to receptors on the cilia. 2  These are 7-pass transmembrane proteins. 3  Binding of the odorant activates a G protein coupled to the receptor on its cytoplasmic side. 4  This activates adenylyl cyclase, an enzyme embedded in the plasma membrane of the cilia.