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Figure 1.
Figure 1 Structure of M761-2R-R238E. Although two molecules are
present in the crystallographic asymmetric unit, only one is
shown here. The two molecules are essentially identical
throughout the myosin motor domain (residues 2 -761). However,
upon leaving the converter domain, the lever arms assume
slightly different orientations and deviate at the ends by 19.4
Å. (A) A complete molecule spanning amino acids 2 -1010 is
shown. No electron density was observed for five residues at the
N-terminus, the loop region 205 -208 and one residue at the
C-terminus. The N-terminal domain (2 -200) is shown in green; 50
kDa domain in red (201 -613); C-terminal and converter domain in
blue (614 -761); linker region in orange (762 -764);  -actinin
lever arm in yellow (765 -1003); and seven histidines from the
His[8] purification tag in gray (1004 -1010). The linker region
is composed of three residues (Leu-Gly-Arg) introduced during
cloning. The observed lever arm is  140
Å long (measured from C of
761 to C of
1010). Each -actinin
repeat contributes 65
Å, and the histidine purification tag another 10 Å. Helices 1 -3
make up the first -actinin
repeat, and 4 -6 the second. The arrowhead indicates the -helical
region linking the two repeats. The disruptive kink in helix 2
is caused by the presence of two adjacent proline residues (see
Figure 4A). (B) Detailed view of the linker region joining the
myosin converter domain to helix 1 of -actinin.
The view is rotated 180° around a vertical axis from that in (A).
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