A handful of engineered or structurally unusual peptides beat this barrier
The luciferin formed is detected in a coupled reaction using Ultra-Glo Recombinant Luciferase that generates a glow-type luminescence that is proportional to the amount of glutathione present in cells
Similar to the E/DRY motif of class A GPCR, Class B GPCRs contain several highly conserved transmembrane polar residues, such as R190 2.60 , N240 3.43 , H363 6.52 , and Q394 7.49 that form the central polar networks (Figure 17) involving TM2TM3TM6TM7 (H180 2.50 , E247 3.50 , T353 6.42 , Y402 7.57 ) and TM2-TM6-TM7-H8 (R176 2.46 , R348 6.37 , N406 7.61 , E408 8.49 ) at the cytoplasmic face that lock the base of the receptors in the inactive state (Wootten et al., 2013)
Acta 1833 , 24302437 (2013)