Practice Questions

TLS Online TPP Program

#Question id: 2882

SUMO (small ubiquitin-related modifier) proteins are ∼10-kD polypeptides that function as reversible post-translational protein modifiers. They form isopeptide bonds with ɛ-amino groups of acceptor Lys residues in hundreds of target proteins in a process termed as sumoylation. Which of the following statements is correct regarding this modification?

#Unit 2. Cellular Organization

A short non-covalent SUMO-interaction/binding motif (SIM/SBM) has been identified in all SUMO enzymes, targets and downstream effectors. This motif contributes to the mechanism and consequences of sumoylation.
Acceptor Lys residues in target proteins are frequently found in the consensus motif ΨKxD although the number of targets with non-consensus acceptor sites is steadily increasing.
Irreversible sumoylation contributes to many distinct pathways, such as chromatin structure, DNA repair, transcription, cell-cycle progression and trafficking.
Sumoylation alters the molecular interactions of modified target proteins by masking or adding interaction surfaces. Downstream consequences, which are target dependent, include changes in localization, activity and protein stability.