Tryptic phosphopeptide maps of WT Towne, OcDNA, T541A, and A463T IEP86. The bottom panel shows a schematic phosphopeptide map of WT Towne with the prominent phosphopeptides labeled A, B, C, D/D′, and E (12). Mutations affecting some of the peptides are shown. For easier comparison of the data, identical lines are drawn connecting phosphopeptides C, B, and D′ in each panel.