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Figure 1.
Figure 1. Overall Structure of the Heterotrimeric PP2A
Holoenzyme Bound to Microcystin-LR (MCLR)
(A) Overall
structure of the PP2A holoenzyme bound to MCLR. The scaffolding
(Aα), catalytic (Cα), and regulatory B′/PR61 (B′-γ1)
subunits are shown in green, blue, and yellow, respectively.
MCLR is shown in magenta. B′-γ1 interacts with both Aα and
Cα through extensive interfaces. Cα interacts with Aα as
described (Xing et al., 2006). Three views are shown here to
reveal the essential features of the holoenzyme. Surprisingly,
B′-γ1 adopts a structure that closely resembles that of the
scaffolding subunit (discussed in detail later).
(B) A
surface representation of the PP2A holoenzyme. Aα and B′-γ1
are shown in surface representation. Cα is shown in backbone
worm to highlight the observation that the carboxyl terminus of
Cα binds to a surface groove at the interface between Aα and
B′-γ1. Figures 1A, 2A, 4A, and 4E were prepared using GRASP
(Nicholls et al., 1991); all other structural figures were made
using MOLSCRIPT (Kraulis, 1991).
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