Odorant receptor-mediated signaling in the mouse.

In the mouse olfactory system, there are approximately 1000 types of odorant receptors (ORs), which perform multiple functions in olfactory sensory neurons (OSNs). In addition to detecting odors, the functional OR protein ensures the singular gene choice of the OR by negative-feedback regulation. ORs also direct the axonal projection of OSNs both globally and locally by modulating the transcriptional levels of axon-guidance and axon-sorting molecules. In these latter processes, the second messenger, cAMP, plays differential roles in the fasciculation and targeting of axons. In this review, we will discuss how ORs differentially regulate intracellular signals for distinct functions.