HG may be partially O-acetylated at C-2 or C-3 of GalA (198, 199). No gene for HG acetyltransferase has been identified; however, O-acetyltransferase activity in microsomes from suspension-cultured potato cells (339) has been shown to transfer [14C]acetate from [14C]acetyl-CoA onto endogenous acceptor in the microsomes to yield a salt/ethanol pre — cipitable product from which approximately 8% of the radioactivity could be solubilized by treatment with endopolygalacturonase and pectin methylesterase. Such results could indicate the presence of HG-AT, although the possibility that the radiolabeled acetate was transferred either onto RG-II or RG-I that was solubilized by the glycanase treatments, and thus represents an enzyme that acetylates one of the other pectic polysaccharides that may be covalently linked to HGA, cannot be ruled out.