Amatoxins and phallotoxins are 8- and 7-membered natural products, respectively, characterized by N-to-C cyclization in addition to a tryptathionine motif derived from the crosslinking of Cys and Trp. The amatoxins and phallotoxins also differ from other RiPPs based on the presence of a C-terminal recognition sequence in addition to the N-terminal leader peptide. α-Amanitin, an amatoxin, has a number of posttranslational modifications in addition to macrocyclization and formation of the tryptathionine bridge: oxidation of the tryptathionine leads to the presence of a sulfoxide, and numerous hydroxylations decorate the natural product. As an amatoxin, α-amanitin is an inhibitor of RNA polymerase II.