398751.fig.002a
(a)
398751.fig.002b
(b)
Figure 2: A portion of the B'-and B-regulatory subunits contacts the active site of the C-catalytic subunit. Ribbon diagrams showing a “top-down” view of two heterotrimeric holoenzyme PP2A complexes. The subunits of the holoenzyme complexes are color-coded with the catalytic C subunit in gray, the scaffold A subunit in yellow, and B subunits in blue. The PP2A inhibitor microcystin-LR is shown near the active site as a red stick figure. (a), Structure of the PP2A/B'γ holoenzyme (PDB 2NPP); inset highlights the infiltration of the B'γ-subunit residue, E122 (green), into the catalytic core above. Below, sequence alignment of the B' family of regulatory subunits with the conserved glutamate residue (green). (b), Structure of the PP2A/Bα holoenzyme (PDB 3DW8); inset shows infiltration of the Bα-subunit residues, K88 (green), into the catalytic core above. Below, sequence alignment of the B family of regulatory subunits with the conserved lysine residue (green).