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Updated: May 3, 2026

In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells
Published on: November 2, 2017
Structural basis for E2-mediated SUMO conjugation revealed by a complex between ubiquitin-conjugating enzyme Ubc9 and
Victor Bernier-Villamor1, Deborah A Sampson, Michael J Matunis
1Biochemistry Department, Structural Biology Program, Weill Medical College of Cornell University, New York, NY 10021, USA.
Abstract:
E2 enzymes catalyze attachment of ubiquitin and ubiquitin-like proteins to lysine residues directly or through E3-mediated reactions. The small ubiquitin-like modifier SUMO regulates nuclear transport, stress response, and signal transduction in eukaryotes and is essential for cell-cycle progression in yeast. In contrast to most ubiquitin conjugation, the SUMO E2 enzyme Ubc9 is sufficient for substrate recognition and lysine modification of known SUMO targets. Crystallographic analysis of a complex between mammalian Ubc9 and a C-terminal domain of RanGAP1 at 2.5 A reveals structural determinants for recognition of consensus SUMO modification sequences found within SUMO-conjugated proteins. Structure-based mutagenesis and biochemical analysis of Ubc9 and RanGAP1 reveal distinct motifs required for substrate binding and SUMO modification of p53, IkappaBalpha, and RanGAP1.
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