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 MG 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 Mon Nov 12 15:59:50 2007
