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Figure 5.
Figure 5. Structural Determinants of mSCP2 Cargo Loading onto
Pex5p(C)
(A) Stereo view of the 2F[O] − F[C] electron
density, using phases from the refined model and contoured at
1σ, of the PTS1 motif from mSCP2 (gray) and some interacting
residues from Pex5p and ordered solvent molecules (dark green).
(B) Pex5p(C)/mSCP2 complex formation by two distinct
interfaces: C-terminal PTS1 motif from mSCP2 (orange)-central
cavity of the circular TPR motif structure from Pex5p; secondary
surface from mSCP2-C-terminal helical bundle from Pex5p. Ser600
is in a central position between the two surface patches,
allowing the proper arrangement of the two cargo surface patches
of Pex5p to support binding of mSCP2. The C terminus of the 7C
loop (red) interacts by a few hydrogen bonds with the TPR1
segment.
(C) TPR4 motif of Pex5p(C), as observed in the
cargo-loaded structure of the receptor. Specific interactions
between TPR3 and TPR4, generating a circular conformation of
Pex5p(C), are shown. Colors are as in Figure 3 and Figure 4,
except that some of the bonds of residues from the C-terminal
TPR motifs 5–7 and the 7C loop are colored in gray to allow
illustrations of oxygen and nitrogen atoms. Hydrogen bonds are
shown by dashed lines.
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