Figure 1: Diversity of the B-regulatory subunits and the structure of the PP2A holoenzyme complex. (a) Cladogram of the human PP2A B-regulatory subunits generated using ClustalW [16] and shown with Dendroscope [17]. (b) Structure of the dimeric A scaffold subunit and C catalytic subunit (gray). The shaded portions of the A scaffold subunit indicate the known docking sites for the B regulatory subunits; green (HEAT repeat 1) for the B family of regulatory subunits, red (HEAT repeat 8) for the B' family of regulatory subunits, and yellow (HEAT repeat 2–7) for the docking site area common for the B and B' families. Cartoon structure of the B (green ribbon), B' (red ribbon), B (purple rectangle), and B”' (tan circle) families of regulatory subunits. Cartoon structures were generated using the Protein Data Bank accession codes 3DW8 and 2NPP.