The olfactory system is necessary for environmental perception in animals, where olfactory sensory neurons (OSNs) can detect volatile molecules in the air. For OSNs, terminal maturation is temporally coordinated with, and dependent on, the expression and function of olfactory receptors (ORs) that directly bind to odorants. In mouse, an OR is stochastically selected in a monogenic and monoallelic fashion from 1000 potential ORs, granting each neuron its own unique identity. Though the exact mechanism underlying OR