Figure 6.
Fig. 6. a, the fold of monomeric CDK2. The structure is
shown in a schematic representation with regions of -sheet shown
as arrows and -helix
shown as ribbons. The N-terminal domain is colored principally
white, with the exception of the glycine-rich loop (colored
magenta), and the C-helix (PSTAIRE helix, colored gold). The
region of the N-terminal domain for which no trace is visible
(residues 36-43) is indicated by small black spheres identifying
residues 35 and 44. ATP is shown in ball and stick
representation at the interface between the N- and C-terminal
domains. The C-terminal domain is colored pink, with the
activation segment (residues 145-172) highlighted in cyan. b,
comparison of electron density for the tip of the activation
segment. The upper stereo pair shows electron density defining
the conformation of residues at the tip of the activation
segment (residues 155-165) in the ATP complex of
unphosphorylated monomeric CDK2, while the lower stereo pair
shows the equivalent electron density in phosphorylated
monomeric CDK2. In this figure the phosphate group attached to
Thr^160 has been omitted from the phosphorylated CDK2 structure
for clarity. The maps were calculated using (2F[o] F[c]) [calc]
coefficients generated by REFMAC and are contoured at a level of
0.2e^ Å^
3. c,
B-factor plots for CDK2-ATP and phosphorylated CDK2-ATP. The
mean main chain B-factor of each residue along the polypeptide
chain is shown for unphosphorylated CDK2 (thin lines) and
phosphorylated CDK2 (thick lines). The outstanding regions of
difference include the glycine loop (residues 8-18) and the tip
of the activation segment (residues 155-165). d, detail of the
fold of the CDK2-ATP complex. The interaction of Tyr^159 and
Thr^160, at the tip of the activation segment, with residues
Glu^12-Tyr^15 in the glycine-rich loop is shown. The coloring
scheme is the same as for a.
-sheet shown
as arrows and 
-helix
shown as ribbons. The N-terminal domain is colored principally
white, with the exception of the glycine-rich loop (colored
magenta), and the C-helix (PSTAIRE helix, colored gold). The
region of the N-terminal domain for which no trace is visible
(residues 36-43) is indicated by small black spheres identifying
residues 35 and 44. ATP is shown in ball and stick
representation at the interface between the N- and C-terminal
domains. The C-terminal domain is colored pink, with the
activation segment (residues 145-172) highlighted in cyan. b,
comparison of electron density for the tip of the activation
segment. The upper stereo pair shows electron density defining
the conformation of residues at the tip of the activation
segment (residues 155-165) in the ATP complex of
unphosphorylated monomeric CDK2, while the lower stereo pair
shows the equivalent electron density in phosphorylated
monomeric CDK2. In this figure the phosphate group attached to
Thr^160 has been omitted from the phosphorylated CDK2 structure
for clarity. The maps were calculated using (2F[o] 
F[c]) 
Å^