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PDBsum entry 1okc
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Transport protein
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PDB id
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1okc
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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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Structure of mitochondrial ADP/ATP carrier in complex with carboxyatractyloside.
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Authors
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E.Pebay-Peyroula,
C.Dahout-Gonzalez,
R.Kahn,
V.Trézéguet,
G.J.Lauquin,
G.Brandolin.
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Ref.
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Nature, 2003,
426,
39-44.
[DOI no: ]
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PubMed id
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Abstract
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ATP, the principal energy currency of the cell, fuels most biosynthetic
reactions in the cytoplasm by its hydrolysis into ADP and inorganic phosphate.
Because resynthesis of ATP occurs in the mitochondrial matrix, ATP is exported
into the cytoplasm while ADP is imported into the matrix. The exchange is
accomplished by a single protein, the ADP/ATP carrier. Here we have solved the
bovine carrier structure at a resolution of 2.2 A by X-ray crystallography in
complex with an inhibitor, carboxyatractyloside. Six alpha-helices form a
compact transmembrane domain, which, at the surface towards the space between
inner and outer mitochondrial membranes, reveals a deep depression. At its
bottom, a hexapeptide carrying the signature of nucleotide carriers (RRRMMM) is
located. Our structure, together with earlier biochemical results, suggests that
transport substrates bind to the bottom of the cavity and that translocation
results from a transient transition from a 'pit' to a 'channel' conformation.
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Figure 5.
Figure 5: The binding of CATR. a, Chemical formula of CATR.
b, CATR within the binding pocket viewed from the outside. c,
Electron density map at 2.2 Å resolution (2F[obs] - F[calc],
contoured at 1  obtained
before CATR modelling and including only protein atoms) around
CATR. Residues directly within hydrogen-bond distances to CATR
are labelled. Black arrowheads indicate van der Waals contacts
between CATR and the protein. d, A close-up of the two CATR
carboxylates interacting with arginines. Interatomic distances
are given in Å.
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Figure 6.
Figure 6: The closed conformation of the carrier viewed from the
matrix. Only odd-numbered helices are represented. Residues
involved in the PX(D/E)XX(K/R) sequence are labelled. Black
lines connect atoms within hydrogen-bonding distances (in Å).
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(2003,
426,
39-44)
copyright 2003.
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