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Figure 6.
Figure 6 Observed and hypothetical modes of polyphosphoinositide
recognition. Schematic diagram depicting potential modes of
polyphosphoinositide recognition by PH domains. The orientation
of the inositol ring and disposition of phosphate groups are
categorized with respect to the location of inorganic
sulfate/phosphate ions observed in the unliganded structures of
the 2G Grp1 and Dapp1 PH domains. Blue circles represent the
phosphate binding site corresponding to the most buried and
electropositive region of the head group binding site formed
primarily by the N-terminal lysine and C-terminal arginine
residue of the signature motif. Yellow circles represent the
phosphate binding site comprised of the N-terminal lysine
residue from the signature motif as well as basic and/or polar
residues from the variable SDRs. In this classification of
binding modes, rotational and/or translational displacements of
the inositol ring that are not sufficiently large to alter the
network of interactions with conserved residues are neglected as
are the specific rotomer conformations of the phosphate groups.
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