lexAop regulates expression of a BacTrace sensor construct beginning with the Syn21 5' UTR, followed by QF2 fused to amino acids 141-206 from human SNAP25 (flanked by Tag:V5 at the 5' end and Tag:FLAG at the 3' end), followed by full length Syx1A (to target the inactive sensor to the synaptic membrane). (GenBank MN658780.)