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[[Image:1hk4.gif|left|200px]]<br />
<applet load="1hk4" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1hk4, resolution 2.40&Aring;" />
'''HUMAN SERUM ALBUMIN COMPLEXED WITH THYROXINE (3,3',5,5'-TETRAIODO-L-THYRONINE) AND MYRISTIC ACID (TETRADECANOIC ACID)'''<br />


==Overview==
==HUMAN SERUM ALBUMIN COMPLEXED WITH THYROXINE (3,3',5,5'-TETRAIODO-L-THYRONINE) and myristic acid (tetradecanoic acid)==
Human serum albumin (HSA) is the major protein component of blood plasma, and serves as a transporter for thyroxine and other hydrophobic compounds, such as fatty acids and bilirubin. We report here a structural, characterization of HSA-thyroxine interactions. Using crystallographic, analyses we have identified four binding sites for thyroxine on HSA, distributed in subdomains IIA, IIIA, and IIIB. Mutation of residue R218, within subdomain IIA greatly enhances the affinity for thyroxine and, causes the elevated serum thyroxine levels associated with familial, dysalbuminemic hyperthyroxinemia (FDH). Structural analysis of two FDH, mutants of HSA (R218H and R218P) shows that this effect arises because, substitution of R218, which contacts the hormone bound in subdomain IIA, produces localized conformational changes to relax steric restrictions on, thyroxine binding at this site. We have also found that, although fatty, acid binding competes with thyroxine at all four sites, it induces, conformational changes that create a fifth hormone-binding site in the, cleft between domains I and III, at least 9 A from R218. These structural, observations are consistent with binding data showing that HSA retains a, high-affinity site for thyroxine in the presence of excess fatty acid that, is insensitive to FDH mutations.
<StructureSection load='1hk4' size='340' side='right'caption='[[1hk4]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1hk4]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HK4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1HK4 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MYR:MYRISTIC+ACID'>MYR</scene>, <scene name='pdbligand=T44:3,5,3,5-TETRAIODO-L-THYRONINE'>T44</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1hk4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1hk4 OCA], [https://pdbe.org/1hk4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1hk4 RCSB], [https://www.ebi.ac.uk/pdbsum/1hk4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1hk4 ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/ALBU_HUMAN ALBU_HUMAN] Defects in ALB are a cause of familial dysalbuminemic hyperthyroxinemia (FDH) [MIM:[https://omim.org/entry/103600 103600]. FDH is a form of euthyroid hyperthyroxinemia that is due to increased affinity of ALB for T(4). It is the most common cause of inherited euthyroid hyperthyroxinemia in Caucasian population.<ref>PMID:8048949</ref> <ref>PMID:7852505</ref> <ref>PMID:9329347</ref> <ref>PMID:9589637</ref>
== Function ==
[https://www.uniprot.org/uniprot/ALBU_HUMAN ALBU_HUMAN] Serum albumin, the main protein of plasma, has a good binding capacity for water, Ca(2+), Na(+), K(+), fatty acids, hormones, bilirubin and drugs. Its main function is the regulation of the colloidal osmotic pressure of blood. Major zinc transporter in plasma, typically binds about 80% of all plasma zinc.<ref>PMID:19021548</ref>
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/hk/1hk4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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=1hk4 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Human serum albumin (HSA) is the major protein component of blood plasma and serves as a transporter for thyroxine and other hydrophobic compounds such as fatty acids and bilirubin. We report here a structural characterization of HSA-thyroxine interactions. Using crystallographic analyses we have identified four binding sites for thyroxine on HSA distributed in subdomains IIA, IIIA, and IIIB. Mutation of residue R218 within subdomain IIA greatly enhances the affinity for thyroxine and causes the elevated serum thyroxine levels associated with familial dysalbuminemic hyperthyroxinemia (FDH). Structural analysis of two FDH mutants of HSA (R218H and R218P) shows that this effect arises because substitution of R218, which contacts the hormone bound in subdomain IIA, produces localized conformational changes to relax steric restrictions on thyroxine binding at this site. We have also found that, although fatty acid binding competes with thyroxine at all four sites, it induces conformational changes that create a fifth hormone-binding site in the cleft between domains I and III, at least 9 A from R218. These structural observations are consistent with binding data showing that HSA retains a high-affinity site for thyroxine in the presence of excess fatty acid that is insensitive to FDH mutations.


==Disease==
Structural basis of albumin-thyroxine interactions and familial dysalbuminemic hyperthyroxinemia.,Petitpas I, Petersen CE, Ha CE, Bhattacharya AA, Zunszain PA, Ghuman J, Bhagavan NV, Curry S Proc Natl Acad Sci U S A. 2003 May 27;100(11):6440-5. Epub 2003 May 12. PMID:12743361<ref>PMID:12743361</ref>
Known diseases associated with this structure: Analbuminemia OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=103600 103600]], Dysalbuminemic hyperthyroxinemia OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=103600 103600]], Dysalbuminemic hyperzincemia OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=103600 103600]]


==About this Structure==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
1HK4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with MYR and T44 as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1HK4 OCA].
</div>
<div class="pdbe-citations 1hk4" style="background-color:#fffaf0;"></div>


==Reference==
==See Also==
Structural basis of albumin-thyroxine interactions and familial dysalbuminemic hyperthyroxinemia., Petitpas I, Petersen CE, Ha CE, Bhattacharya AA, Zunszain PA, Ghuman J, Bhagavan NV, Curry S, Proc Natl Acad Sci U S A. 2003 May 27;100(11):6440-5. Epub 2003 May 12. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=12743361 12743361]
*[[Albumin 3D structures|Albumin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Bhagavan, N.V.]]
[[Category: Bhagavan NV]]
[[Category: Bhattacharya, A.A.]]
[[Category: Bhattacharya AA]]
[[Category: Curry, S.]]
[[Category: Curry S]]
[[Category: Ghuman, J.]]
[[Category: Ghuman J]]
[[Category: Ha, C.E.]]
[[Category: Ha CE]]
[[Category: Petersen, C.E.]]
[[Category: Petersen CE]]
[[Category: Petitpas, I.]]
[[Category: Petitpas I]]
[[Category: Zunszain, P.A.]]
[[Category: Zunszain PA]]
[[Category: MYR]]
[[Category: T44]]
[[Category: familial dysalbuminemic hyperthyroxinemia]]
[[Category: hormone-binding]]
[[Category: lipid-binding]]
[[Category: plasma protein]]
[[Category: thyroxine]]
 
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