1am9
From Proteopedia
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HUMAN SREBP-1A BOUND TO LDL RECEPTOR PROMOTER
Overview
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-->Tyr substitution yields dramatically different DNA-binding properties that explain how they recognize StREs and regulate expression of genes important for membrane biosynthesis.
About this Structure
1AM9 is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Thu Feb 21 11:45:59 2008
