Figure 2. Western blot analysis of the recombinant glutathione-S-transferase (GST)-fusion proteins produced in bacteria. Recombinant GST and GST-fusion proteins were detected with a monoclonal anti-GST antibody. MW, molecular weight ladder is expressed in kDa. A: Similar amounts of proteins extracted from the bacterial cultures before (ni) and after (i) induction with Isopropyl β-D-thiogalactoside (IPTG) were loaded. The expected molecular weight of the full-length fusion protein is indicated with *. A protein of 29.9 kDa is expected for empty vector pKE-1. It contains the 26.5 kDa GST sequence with some additional amino acids at the C-terminus. Dimers of the GST protein (~60 kDa) were also observed. B: The amount of the full-length GST fusion proteins (*) produced in the bacteria was estimated using purified recombinant GST protein as a reference. Bacterial extracts from 5 and 25 µl induced culture and known amounts of a recombinant GST protein (26.5 kDa) were loaded. The amount (ng) of the GST portion of the full-length fusion protein was visually evaluated in comparison with the purified GST protein and converted into the corresponding number of moles of GST and hence of the protein fused to GST.