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PDBsum entry 1rl3
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Rialpha subunit of pka: a camp-Free structure reveals a hydrophobic capping mechanism for docking camp into site b.
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Authors
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J.Wu,
S.Brown,
N.H.Xuong,
S.S.Taylor.
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Ref.
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Structure, 2004,
12,
1057-1065.
[DOI no: ]
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PubMed id
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Abstract
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In eukaryotes the primary target for cAMP, a ubiquitous second messenger, is
cAMP-dependent protein kinase (PKA). Understanding how binding and release of
cAMP changes the cAMP binding domains and then triggers long-range allosteric
responses is an important challenge. This conformational switching requires
structure solutions of cAMP binding domains in cAMP-bound and cAMP-free states.
We describe for the first time a crystal structure of the cAMP binding domains
of PKA type Ialpha regulatory subunit where site A is occupied by cGMP and site
B is unoccupied. The structure reveals that the carboxyl terminus of domain B
serves as a hydrophobic cap, locking the cyclic nucleotide via its adenine ring
into the beta-barrel. In the absence of cAMP, the "cap" is released
via an extension of the C-terminal helix. This simple hinge mechanism for
binding and release of cAMP also provides a mechanism for allosteric
communication between sites A and B.
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Figure 6.
Figure 6. The Domain Organization and the Functional Sites
of RIa Are HighlightedDomain B is in light blue, domain A is
dark blue, and the N-terminal segment preceding the domain is in
tan. The C helices and PBC motifs in domain A and B are shown in
red and orange, respectively.
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2004,
12,
1057-1065)
copyright 2004.
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