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Figure 3.
Figure 3. Electrostatic surface of LC1 and proposed heavy chain
binding site. a, Two views (related by 90° rotation about the
y-axis) of the electrostatic surface of LC1 are shown. The
hydrophobic patch, which includes Trp 99, Tyr 121 and Leu 146 on
the  -sheet
face, is evident in the view on the right. It is this patch that
may be involved in attachment of LC1 to the  heavy
chain. The opposite surface proposed to interact with p45 (left
view) is highly charged, with patches of both acidic and basic
residues. The surface potential was calculated using dielectric
constants of 30 and 80 for protein and solvent, respectively.
The images are oriented with the N-terminus to the top. b, Close
up stereo view of the putative heavy
chain binding surface. Side chains at positions that are
hydrophobic in all family members are shown in green (Trp 99 and
Leu 146), whereas hydrophobic side chains at less conserved
positions are in yellow (Ile 74, Tyr 102, Val 119 and Tyr 121).
Acidic and basic residues that surround the hydrophobic patch
are shown in red and blue, respectively. c, The superimposed
ribbon structures of LC1 (orange) and U2A' (yellow; accession
code 1A9N) are shown to illustrate the structural homology
between these two molecules. The r.m.s. deviation for
superimposed C  atoms
is 3.7 Å as determined by DALI (version 2.0)30.
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