Plant cell-wall polysaccharides containing predominantly arabinose and galactose. Two main types are recognized: arabinogalactan 1, found in the pectin portion of angiosperms and containing a (1-4) -linked galactan and a -arabinose side-chains; arabinogalactan II, a highly branched polymer containing b (1-3) - and b (1-6) -linked galactose and peripheral a -arabinose residues. Arabinogalactan II is found in large amounts on some gymnosperms, especially larches, and is related to AGP.
Dictionary of molecular biology. 2004.