Protein that filters odour information

A 30 year-old mystery surrounding the function of a protein in our smell receptors has been solved after researchers revealed it plays a vital role in filtering data from smell receptors. The findings suggest that olfactory marker protein (OMP), a molecule found in the cells that detect odour molecules, plays a key role in regulating the speed and transmission of odour information to the brain. Led by researchers from the Monell Center, the study solves a three-decade-old mystery regarding the function of OMP, and increases understanding of how the olfactory system integrates information to transmit accurate data about odours and the messages they contain. "At any one time, thousands of different odour molecules arrive at the smell receptors in our noses to provide detailed information about the surrounding world. OMP helps the smell receptor cells filter this vast amount of information so that animals can respond appropriately," said Monell cellular physiologist Johannes Reisert, PhD, the study's senior author. Smell signalling Writing in the Journal of Neuroscience, the team explained that the process of converting the chemical information from an odour molecule into an electrical signal that can be transmitted to the brain is controlled by a complex sequence of molecular events called olfactory transduction. Although scientists previously knew that OMP had a role in this process, the exact nature of its role was unclear, until now. In the new study, Reisert and his team found that OMP – expressed in mature smell receptors known as olfactory receptor neurons (ORNs) – controls the level of signalling from receptors to the brain by filtering out base levels from ‘background noise’. In mice genetically engineered to lack OMP, the Monell researchers saw a resulting increase in base levels of cellular signals known as cAMP. This increase in base levels blocked differentiation between cellular signals from ‘background’ and a true stimulus. "What this tells us is that OMP dampens cAMP 'noise' to allow the olfactory system to differentiate between odorant receptors and to allow faithful transmission of odour information to the brain," said Reisert. "Understanding how olfactory marker protein and the odorant receptors dictate olfactory receptor neuron responses will help drive the direction of future studies to understand how ORNs contribute to our ability to experience and respond to our olfactory world," added Michele Dibattista, first author of the study. Source: Journal of Neuroscience Volume 36, Issue 10, Pages 2995-3006, doi: 10.1523/JNEUROSCI.4209-15.2016 “The Odorant Receptor-Dependent Role of Olfactory Marker Protein in Olfactory Receptor Neurons” Authors: M. Dibattista, J. Reisert