2akq

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[[Image:2akq.gif|left|200px]]
 
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{{Structure
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==The structure of bovine B-lactoglobulin A in crystals grown at very low ionic strength==
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|PDB= 2akq |SIZE=350|CAPTION= <scene name='initialview01'>2akq</scene>, resolution 3.00&Aring;
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<StructureSection load='2akq' size='340' side='right'caption='[[2akq]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
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|SITE=
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== Structural highlights ==
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|LIGAND=
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<table><tr><td colspan='2'>[[2akq]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1mfh 1mfh]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AKQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2AKQ FirstGlance]. <br>
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|ACTIVITY=
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3&#8491;</td></tr>
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|GENE=
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2akq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2akq OCA], [https://pdbe.org/2akq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2akq RCSB], [https://www.ebi.ac.uk/pdbsum/2akq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2akq ProSAT]</span></td></tr>
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}}
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/LACB_BOVIN LACB_BOVIN] Primary component of whey, it binds retinol and is probably involved in the transport of that molecule.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ak/2akq_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2akq ConSurf].
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<div style="clear:both"></div>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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Bovine beta-lactoglobulin (BLG) is a globular protein of uncertain physiological function and a member of the lipocalin superfamily of proteins. Here, we present the X-ray structure at 3.0 angstroms of BLG (variant A) from an orthorhombic (P2(1)2(1)2(1)) pseudo-tetragonal crystal form that suffers from pseudo-merohedral twinning (final R(working) = 0.224, R(free) = 0.265). Crystals were grown by dialysis against ultra-purified water (i.e., at very low ionic strength), at pH approximately 5.2 (approximately pI), conditions vastly different from all other BLG structures determined previously. This allows critical assessment of the BLG structure and of the influence that pH, ionic strength, and crystal packing may have on the molecular structure of BLG. The pH-sensitive EF loop is found in the closed conformation characteristic of BLG at pH less than 7 and moderate to high ionic strength. Although the hydrophobic pocket appears to be empty, the presence of highly disordered water molecules cannot be excluded. The dimer interface and the hydrophobic pocket (calyx) are preserved. However, the orientation of the subunits in the dimer varies considerably with crystal form. Structure is deposited with PDB ID 2akq.
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'''The structure of bovine B-lactoglobulin A in crystals grown at very low ionic strength'''
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Structure of bovine beta-lactoglobulin (variant A) at very low ionic strength.,Adams JJ, Anderson BF, Norris GE, Creamer LK, Jameson GB J Struct Biol. 2006 Jun;154(3):246-54. Epub 2006 Feb 6. PMID:16540345<ref>PMID:16540345</ref>
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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</div>
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<div class="pdbe-citations 2akq" style="background-color:#fffaf0;"></div>
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==Overview==
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==See Also==
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BACKGROUND: beta-Lactoglobulin (beta-Lg) is the major whey protein in the milk of ruminants and many other mammals. Its function is not known, but it undergoes at least two pH-dependent conformational changes which may be important. Bovine beta-Lg crystallizes in several different lattices, and medium-resolution structures of orthorhombic lattice Y and trigonal lattice Z have been published. Triclinic lattice X and lattice Z crystals grow at pH values either side of the pH at which one of the pH-induced conformational changes occurs. A full understanding of the structure is needed to help explain both the conformational changes and the different denaturation behaviour of the genetic variants. RESULTS: We have redetermined the structure of beta-Lg lattice Z at 3.0 A resolution by multiple isomorphous replacement and have partially refined it (R factor = 24.8%). Using the dimer from this lattice Z structure as a search model, the triclinic crystal form grown at pH 6.5 (lattice X) has been solved by molecular replacement. Refinement of lattice X at 1.8 A resolution gave an R factor of 18.1%. The structure we have determined differs from previously published structures in several ways. CONCLUSIONS: Incorrect threading of the sequence in the published structures of beta-Lg affects four of the nine beta strands. The basic lipocalin fold of the polypeptide chain is unchanged, however. The relative orientation of the monomers in the beta-Lg dimer differs in the two lattices. On raising the pH, there is a rotation of approximately 5 degrees, which breaks a number of intersubunit hydrogen bonds. It is not yet clear, however, why the stability of the structure should depend so heavily upon the external loop around residue 64 or the beta strand with the free thiol, each of which shows genetic variation.
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*[[Beta-lactoglobulin 3D structures|Beta-lactoglobulin 3D structures]]
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== References ==
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==About this Structure==
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<references/>
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2AKQ is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. This structure supersedes the now removed PDB entry 1MFH. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AKQ OCA].
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__TOC__
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</StructureSection>
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==Reference==
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Bovine beta-lactoglobulin at 1.8 A resolution--still an enigmatic lipocalin., Brownlow S, Morais Cabral JH, Cooper R, Flower DR, Yewdall SJ, Polikarpov I, North AC, Sawyer L, Structure. 1997 Apr 15;5(4):481-95. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9115437 9115437]
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[[Category: Bos taurus]]
[[Category: Bos taurus]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Adams, J J.]]
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[[Category: Adams JJ]]
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[[Category: Anderson, B F.]]
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[[Category: Anderson BF]]
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[[Category: Creamer, L K.]]
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[[Category: Creamer LK]]
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[[Category: Jameson, G B.]]
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[[Category: Jameson GB]]
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[[Category: Norris, G E.]]
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[[Category: Norris GE]]
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[[Category: b-lactoglbulin]]
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[[Category: crystal lattice]]
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[[Category: low ionic strength]]
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[[Category: pseudo-merohedral twinning]]
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[[Category: x-ray]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 15:50:49 2008''
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Current revision

The structure of bovine B-lactoglobulin A in crystals grown at very low ionic strength

PDB ID 2akq

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