C. TF:proOmpA:SecB supercomplex analysis using GPC-MALS in Buffer A. TF1:proOmpA1 (10 µM each; green), SecB4 (40 µM; blue) and TF1:proOmpA1:SecB4 (10, 10 and 40 µM, respectively; black). n= 5 biological replicates; mean mass: 137 kDa (± 6 kDa) representative experiment shown; red circles: determined mass (kDa); AU: arbitrary units. 