==HUMAN SREBP-1A BOUND TO LDL RECEPTOR PROMOTER==

<StructureSection load='1am9' size='340' side='right'caption='[[1am9]], [[Resolution|resolution]] 2.30&Aring;' scene=''>

<table><tr><td colspan='2'>[[1am9]] is a 8 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AM9 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1AM9 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1am9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1am9 OCA], [http://pdbe.org/1am9 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1am9 RCSB], [http://www.ebi.ac.uk/pdbsum/1am9 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1am9 ProSAT]</span></td></tr>

== Function ==

[[http://www.uniprot.org/uniprot/SRBP1_HUMAN SRBP1_HUMAN]] Transcriptional activator required for lipid homeostasis. Regulates transcription of the LDL receptor gene as well as the fatty acid and to a lesser degree the cholesterol synthesis pathway (By similarity). Binds to the sterol regulatory element 1 (SRE-1) (5'-ATCACCCCAC-3'). Has dual sequence specificity binding to both an E-box motif (5'-ATCACGTGA-3') and to SRE-1 (5'-ATCACCCCAC-3').

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== Publication Abstract from PubMed ==

BACKGROUND: The sterol regulatory element binding proteins (SREBPs) are helix-loop-helix transcriptional activators that control expression of genes encoding proteins essential for cholesterol biosynthesis/uptake and fatty acid biosynthesis. Unlike helix-loop-helix proteins that recognize symmetric E-boxes (5'-CANNTG-3'), the SREBPs have a tyrosine instead of a conserved arginine in their basic regions. This difference allows recognition of an asymmetric sterol regulatory element (StRE, 5'-ATCACCCAC-3'). RESULTS: The 2.3 A resolution co-crystal structure of the DNA-binding portion of SREBP-1a bound to an StRE reveals a quasi-symmetric homodimer with an asymmetric DNA-protein interface. One monomer binds the E-box half site of the StRE (5'-ATCAC-3') using sidechain-base contacts typical of other helix-loop-helix proteins. The non-E-box half site (5'-GTGGG-3') is recognized through entirely different protein-DNA contacts. CONCLUSIONS: Although the SREBPs are structurally similar to the E-box-binding helix-loop-helix proteins, the Arg--&gt;Tyr substitution yields dramatically different DNA-binding properties that explain how they recognize StREs and regulate expression of genes important for membrane biosynthesis.

Co-crystal structure of sterol regulatory element binding protein 1a at 2.3 A resolution.,Parraga A, Bellsolell L, Ferre-D'Amare AR, Burley SK Structure. 1998 May 15;6(5):661-72. PMID:9634703<ref>PMID:9634703</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Human]]

[[Category: Burley, S K]]

[[Category: Basic-helix-loop-helix-leucine zipper]]

[[Category: Transcription-dna complex]]