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PDBsum entry 1rcm
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Hydrolase(o-glycosyl)
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PDB id
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1rcm
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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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Crystal structure of a ubiquitin-Dependent degradation substrate: a three-Disulfide form of lysozyme.
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Authors
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C.P.Hill,
N.L.Johnston,
R.E.Cohen.
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Ref.
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Proc Natl Acad Sci U S A, 1993,
90,
4136-4140.
[DOI no: ]
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PubMed id
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Abstract
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Covalent attachment of ubiquitin marks substrates for proteolysis, but features
that identify ubiquitination targets such as chicken egg white lysozyme are
poorly understood. Recognition of lysozyme first requires reduction of Cys-6
Cys-127, one of its four native disulfide bonds, and
Cys-6,Cys-127-carboxymethylated (6,127-rcm) lysozyme can mimic this
three-disulfide intermediate. The 6,127-rcm form of lysozyme is known to retain
a substantially native-like conformation in solution, and we demonstrate that it
is this folded structure that is recognized for ubiquitination. Because native
lysozyme is not a substrate, differences between the native and three-disulfide
structures must include features responsible for selective ubiquitination. The
1.9-A resolution crystal structure of 6,127-rcm-lysozyme, reported here, affords
a view of this ubiquitin-dependent degradation substrate. Two conformers of
6,127-rcm-lysozyme were obtained in the crystal. These differ uniquely from
crystal forms of native lysozyme by displacement of the C-terminal residues. The
structures suggest that localized unfolding at the C terminus of three-disulfide
lysozyme allows the complex of E3 alpha (ubiquitin-protein ligase) and E2
(ubiquitin-carrier protein) to bind to a surface that includes Lys-1 and the
putative ubiquitination site Lys-13. From this we infer that the N-terminal and
internal substrate recognition sites on the E3 alpha.E2 complex are separated by
approximately 20 A.
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Secondary reference #1
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Title
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Specific disulfide cleavage is required for ubiquitin conjugation and degradation of lysozyme.
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Authors
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R.L.Dunten,
R.E.Cohen,
L.Gregori,
V.Chau.
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Ref.
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J Biol Chem, 1991,
266,
3260-3267.
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PubMed id
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