Alr3234::GFP Western Blot Analysis in E. coli and Nostoc

For Alr3234::GFP Western blot analysis in E. coli, cells from stationary-phase cultures were harvested and resuspended in SDS-PAGE loading buffer. Proteins were fractionated in 10% SDS–PAGE. Antibodies against GFP (Roche) and E. coli GroEL (Sigma-Aldrich) were used. For Alr3234::GFP Western blot analysis in Nostoc, soluble fractions were prepared as previously described (40 (link)). Forty-microgram amounts of protein were fractionated on 10% SDS–PAGE gels, and Antibodies against GFP were used. Ponceau staining was used as a loading control. The ECL plus immunoblotting system (GE Healthcare) was used to detect the different primary antibodies using anti-rabbit (Sigma-Aldrich) or anti-mouse (Bio-Rad) horseradish peroxidase-conjugated secondary antibodies.