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Figure 2.
Figure 2. Aspects of the rhCK2a^DC structure. (a) Folding
of the monomer drawn in rainbow colors. A view was chosen that
shows the attachment of the N-terminal segment to the activation
segment and to helix aC. The equivalents of these regions and
the b4/b5 loop as found in maize CK2a (PDB code 1LP4) are drawn
in black. (b) Stereo picture of the cosubstrate-binding site.
The AMPPNP molecule is covered with s[A]-weighted (F[o] -F[c])
OMIT density[30] colored in blue and drawn above a cutoff level
of 2.7s above the average. The OMIT map was calculated with CNS
[31] after a 2000 K simulated annealing run in which the AMPPNP
molecule had been omitted. The surrounding protein is embedded
in the final s[A]-weighted (2F[o] -F[c]) electron density (green
color; cutoff level 1.4s above the average). ATP as bound to
CAPK is drawn in black after superimposition of the protein
matrices. (c) Stereo picture of the b4/b5 loop covered by
s[A]-weighted (2F[o] -F[c]) electron density with a cutoff level
of 1.0s above the average. For comparison, the equivalent region
of rhCK2a^DC within the CK2 holoenzyme is drawn in black.
Furthermore a part of the CK2b-dimer is shown in black to
illustrate that the b4/b5-loop conformation in isolated
rhCK2a^DC is not compatible with CK2b binding. All parts of the
Figure were prepared with BOBSCRIPT[41] and RASTER3D. [42]
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