“…RG-II has a backbone of ␣-1,4-linked d-galactosyluronic acid with structurally complex side chains attached to C-2 and/or C-3 (2,157,159,269,(345)(346)(347)(348)(349)(350)(351)(352). RG-II in the wall exists largely complexed with borate as an RG-II dimer that is cross-linked by a borate diester (159,(352)(353)(354)(355)(356)(357). At least 24 transferase activities are expected to be required for RG-II synthesis.…”