A large family of odorant receptors

Richard Axel and Linda Buck published their fundamental paper in 1991, in which they described the genes coding for a large family of odorant receptors.

The odorant receptors are located on the olfactory receptor cells in the nasal cavity. Each olfactory receptor cell expresses only one type of odorant receptor, and each receptor can detect a limited number of odorant substances.

The olfactory receptor

Each receptor consists of a protein chain that traverses the cell membrane seven times.

When an odorant substance attaches to an olfactory receptor, the shape of the receptor protein is altered, leading to a G protein activation.

An electric signal is triggered in the olfactory receptor neuron and sent to the brain via nerve processes.

Small variations

All odorant receptors are related proteins and differ only in some amino acid residues (indicated in green, blue and red).

The subtle differences in the protein chains explain why the receptors are triggered by different odorant molecules.