Fig. 1. Chemical crosslinking assay in vitro and in vivo. Cytosolic (a) and microsomal (b) fractions and the protoplasts (c) were treated with chemical crosslinkers (BS3 and DSS, respectively). Treated samples were then subjected to SDS-PAGE using a 10% acrylamide gel for (a) and (b) and 7.5% for (c). Proteins that reacted against the anti-PtIGS antibody were detected by western blotting. "I" indicates PtIGS monomer. "II" denotes molecules larger than the monomer.