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PDBsum entry 1vb5
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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 the regulatory subunit of archaeal initiation factor 2b (aif2b) from hyperthermophilic archaeon pyrococcus horikoshii ot3: a proposed structure of the regulatory subcomplex of eukaryotic if2b.
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Authors
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Y.Kakuta,
M.Tahara,
S.Maetani,
M.Yao,
I.Tanaka,
M.Kimura.
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Ref.
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Biochem Biophys Res Commun, 2004,
319,
725-732.
[DOI no: ]
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PubMed id
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Abstract
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Eukaryotic translation initiation factor 2B (eIF2B) is the guanine-nucleotide
exchange factor for eukaryotic initiation factor 2 (eIF2). eIF2B is a
heteropentameric protein composed of alpha- subunits. The alpha, beta, and delta
subunits form a regulatory subcomplex, while the gamma and form a catalytic
subcomplex. Archaea possess homologues of alpha, beta, and delta subunits of
eIF2B. Here, we report the three-dimensional structure of an archaeal regulatory
subunit (aIF2Balpha) from the hyperthermophilic archaeon Pyrococcus horikoshii
OT3 determined by X-ray crystallography at 2.2A resolution. aIF2Balpha consists
of two subdomains, an N-domain (residues 1-95) and a C-domain (residues 96-276),
connected by a long alpha-helix (alpha5: 78-106). The N-domain contains a five
helix bundle structure, while the C-domain folds into the alpha/beta structure,
thus showing similarity to D-ribose-5-phosphate isomerase structure. The
presence of two molecules in the crystallographic asymmetric unit and the gel
filtration analysis suggest a dimeric structure of aIF2Balpha in solution,
interacting with each other by C-domains. Furthermore, the crystallographic
3-fold symmetry generates a homohexameric structure of aIF2Balpha; the
interaction is primarily mediated by the long alpha-helix at the N-domains. This
structure suggests an architecture of the three subunits, alpha, beta, and
delta, in the regulatory subcomplex within eIF2B.
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