Structure and function of a HECT domain ubiquitin-binding site
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Updated: Jun 3, 2026

Functional Characterization of RING-Type E3 Ubiquitin Ligases In Vitro and In Planta
Published on: December 5, 2019
Hyung Cheol Kim1, Alanna M Steffen, Michael L Oldham
1Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA.
Abstract:
The Rsp5 ubiquitin ligase contains a non-covalent binding site for ubiquitin within the amino-terminal lobe (N-lobe) of the HECT domain, and the X-ray crystal structure of the HECT-ubiquitin complex has been determined. Hydrophobic patch residues of ubiquitin (L8, I44, V70) were crucial for interaction with Rsp5, and amino-acid alterations at the Rsp5-binding interface resulted in defects in polyubiquitination. Our results support a model in which the N-lobe-binding site acts to localize and orient the distal end of the ubiquitin chain to promote conjugation of the next ubiquitin molecule.
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