Sections of the multiple sequence alignments of the putative pyrrolysine-containing proteins. (a) A protein known to use UAG read-through, methylamine methyltransferase from M. acetivorans. (b) A putative methyltransferase from M. burtonii. (c) A predicted read-through ORF homologous to a cobalamin biosynthesis protein CobN (gi|20906100|gb|AAM31298.1|, Methanosarcina mazei Goe1) from M. acetivorans. Note the alignment of presumed pyrrolysine residues (denoted as X) with various amino acids.