Biomedical subjects
Publications and source records attributed to Frauke Melchior.
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Small ubiquitin related modifier SUMO-1 and its homologs can be conjugated to a large number of cellular proteins. This involves an enzymatic cascade that resembles ubiquitination, and the modification can be reverted by isopeptidases. SUMOylation does not lead to degradation but instead appears to regulate protein/protein interactions, intracellular localization and protects some modified targets from ubiquitin-dependent degradation. Data collected for more than 30 different target proteins point to two cellular processes, nucleocytoplasmic transport and intranuclear targeting, in which SUMO plays an active role. Here we will focus on links between SUMO and nuclear transport.
Abundance and activity of the tumor suppressor p53 are regulated by many different posttranslational modifications. These include phosphorylation, acetylation, ribosylation, O-glycosylation or ubiquitination. Three years ago, covalent modification with the ubiquitin- related protein SUMO-1 has been added to this list. SUMO-1 resembles ubiquitin both in structure and in the mechanism of attachment, and is reversibly attached to a large number of proteins. Molecular consequences of this dynamic modification vary between targets and include alterations in protein/protein or protein/DNA interactions, changes in localization, enzymatic activity, or stability. A role of SUMOylation in modulating p53 transcriptional activity has been reported, but is still an issue of controversy. Here we will briefly summarize the pathway of SUMOylation and discuss possible implications for p53 function.