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spinqualitylabelsall models PDB ID 1yx6 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
Gene:	PSMD4, MCB1 (Homo sapiens)
Related:	1D3Z, 1TBE
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

Solution Structure of S5a UIM-2/Ubiquitin Complex

Overview

Ubiquitin is a key regulatory molecule in diverse cellular events. How cells determine the outcome of ubiquitylation remains unclear; however, a likely determinant is the specificity of ubiquitin receptor proteins for polyubiquitin chains of certain length and linkage. Proteasome subunit S5a contains two ubiquitin-interacting motifs (UIMs) through which it recruits ubiquitylated substrates to the proteasome for their degradation. Here, we report the structure of S5a (196-306) alone and complexed with two monoubiquitin molecules. This construct contains the two UIMs of S5a and we reveal their different ubiquitin-binding mechanisms and provide a rationale for their unique specificities for different ubiquitin-like domains. Furthermore, we provide direct evidence that S5a (196-306) binds either K63-linked or K48-linked polyubiquitin, and in both cases prefers longer chains. On the basis of these results we present a model for how S5a and other ubiquitin-binding proteins recognize polyubiquitin.

About this Structure

1YX6 is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Structure of S5a bound to monoubiquitin provides a model for polyubiquitin recognition., Wang Q, Young P, Walters KJ, J Mol Biol. 2005 May 6;348(3):727-39. PMID:15826667

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