1umi: Difference between revisions

[[Image:1umi.jpg|left|200px]]<br /><applet load="1umi" size="350" color="white" frame="true" align="right" spinBox="true"  

SCF(Fbs1) is a ubiquitin ligase that functions in the endoplasmic reticulum (ER)-associated degradation pathway. Fbs1/Fbx2, a member of the F-box proteins, recognizes high-mannose oligosaccharides. Efficient binding to an N-glycan requires di-N-acetylchitobiose (chitobiose). Here we report the crystal structures of the sugar-binding domain (SBD) of Fbs1 alone and in complex with chitobiose. The SBD is composed of a ten-stranded antiparallel beta-sandwich. The structure of the SBD-chitobiose complex includes hydrogen bonds between Fbs1 and chitobiose and insertion of the methyl group of chitobiose into a small hydrophobic pocket of Fbs1. Moreover, NMR spectroscopy has demonstrated that the amino acid residues adjoining the chitobiose-binding site interact with the outer branches of the carbohydrate moiety. Considering that the innermost chitobiose moieties in N-glycans are usually involved in intramolecular interactions with the polypeptide moieties, we propose that Fbs1 interacts with the chitobiose in unfolded N-glycoprotein, pointing the protein moiety toward E2 for ubiquitination.

1UMI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Active as [http://en.wikipedia.org/wiki/Ubiquitin--protein_ligase Ubiquitin--protein ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.2.19 6.3.2.19] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1UMI OCA].  

[[Category: Lee, S J.]]

[[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]]

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