text: Diazirines are widely used in receptor labeling studies. This is because diazirine-containing analogs of various ligands can be synthesized and incubated with their respective receptors, and then subsequently exposed to light to produce reactive carbenes. The carbene will covalently bond to residues in the binding site of the receptor. The carbene compound may include a bioorthogonal tag or handle by which the protein of interest can be isolated. The protein can then be digested and sequenced by mass spectrometry in order to identify which residues the carbene containing ligand is bound to, and hence the identity of the binding site in the receptor.
  Examples of diazirines used in receptor labeling studies include:
  * The discovery of a brassinosteroid receptor for brassinosteroid plant hormones by Kinoshita et al. Researchers used a plant hormone analog with a diazirine crosslinking moiety and a biotin tag for isolation to identity the new receptor. This study led to a number of similar studies conducted with regards to other plant hormones. 
  * The discovery of novel non-CB1/CB2 cannabinoid receptors using anandamide analog probes containing a diazirine group by Balas et al.
  * The binding cavity of the hypnotic agent propofol in the GABA receptor using a diazirine containing propofol analog.