Single Cell RT-PCR Identification of Odorant Receptors Expressed by Olfactory Neurons

Mammals have between 400 and 1,300 functional odorant receptor (OR) genes in their genomes. Each olfactory sensory neuron in the nose expresses only one single type of OR out of this vast repertoire. The OR expressed by an olfactory sensory neuron determines its functional activity and wiring to the olfactory bulb. Therefore, the identification of the OR type expressed by individual neurons contributes to the understanding of the mechanisms of odorant perception. Here we describe the protocol that combines single cell RT-PCR and degenerate PCR to identify the OR expressed by single olfactory neurons. In a primary PCR reaction, cDNAs corresponding to all mRNAs present in a single neuron are synthesized. In a secondary PCR reaction, the cDNAs corresponding to the OR expressed by this neuron are amplified using degenerate primers that match OR sequences.