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1xhn
From Proteopedia
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| , resolution 1.95Å | |||||||
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| Ligands: | |||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
The crystal structure of Cellular Repressor of E1A-stimulated Genes (CREG)
Overview
The cellular repressor of E1A-stimulated genes (CREG) is a secreted glycoprotein that inhibits proliferation and enhances differentiation of human embryonal carcinoma cells. CREG binds to the cation-independent mannose 6-phosphate (M6P)/insulin-like growth factor II (IGF2) receptor (IGF2R) (M6P/IGF2R), and this receptor has been shown to be required for CREG-induced growth suppression. To better understand CREG function in cellular growth and differentiation, we solved the 3D crystal structure of this protein to 1.9-A resolution. CREG forms a tight homodimeric complex, and CREG monomers display a beta-barrel fold. The three potential glycosylation sites on CREG map to a confined patch opposite the dimer interface. Thus, dimerization of glycosylated CREG likely presents a bivalent ligand for the M6P/IGF2R. Closely related structural homologs of CREG are FMN-binding split-barrel fold proteins that bind flavin mononucleotide. Our structure shows that the putative flavin mononucleotide-binding pocket in CREG is sterically blocked by a loop and several key bulky residues. A mutant of CREG lacking a part of this loop maintained overall structure and dimerization, as well as M6P/IGF2R binding, but lost the growth suppression activity of WT CREG. Thus, analysis of a structure-based mutant of CREG revealed that binding to M6P/IGF2R, while necessary, is not sufficient for CREG-induced growth suppression. These findings indicate that CREG utilizes a known fold for a previously undescribed function [corrected]
About this Structure
1XHN is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
The crystal structure of CREG, a secreted glycoprotein involved in cellular growth and differentiation., Sacher M, Di Bacco A, Lunin VV, Ye Z, Wagner J, Gill G, Cygler M, Proc Natl Acad Sci U S A. 2005 Dec 20;102(51):18326-31. Epub 2005 Dec 12. PMID:16344469
Page seeded by OCA on Mon Mar 31 00:49:45 2008
