Background：

This gene encodes a protein that is a member of the SUMO (small ubiquitin-like modifier) protein family. It functions in a manner similar to ubiquitin in that it is bound to target proteins as part of a post-translational modification system. However， unlike ubiquitin which targets proteins for degradation， this protein is involved in a variety of cellular processes， such as nuclear transport， transcriptional regulation， apoptosis， and protein stability. It is not active until the last two amino acids of the carboxy-terminus have been cleaved off. Numerous pseudogenes have been reported for this gene. Alternate transcriptional splice variants， encoding different isoforms， have been characterized.