Identification of the odor-active volatile compound (Z,Z)-4,7-tridecadienal as a potential ligand for the transmembrane receptor CD36.

Cluster of differentiation 36 (CD36) is a broadly expressed transmembrane protein that has multiple ligands, including oxidized low-density lipoproteins. We found recently that CD36 is expressed in olfactory sensory neurons and postulated that it plays a role in the detection of distinct odorants in the nasal cavity. To date, however, there have been few examples of attempts to identify CD36-recognizable odorants. In this study, by an in vitro assay using a peptide mimic of the receptor, we provided evidence that CD36 recognizes (Z,Z)-4,7-tridecadienal, an odor-active volatile compound that is known to occur in Katsuobushi (dried, fermented, and smoked skipjack tuna commonly used in Japanese cuisine as a seasoning) and in the preorbital secretion of male oribi. In addition, by comparing the data with those of its related compounds, we provided information on the structural requirements of (Z,Z)-4,7-tridecadienal for recognition by CD36. For instance, we showed that flexible rotation around the C2-C3 bond of the volatile may be of importance in gaining access to CD36. Identification of (Z,Z)-4,7-tridecadienal as the ligand prompts us to hypothesize that CD36 could participate in the control of distinct mammalian behaviors (e.g., food selection) through its ability to recognize specific odorants in the environment.