This gene encodes a member of a family of E3 small ubiquitin-related modifier (SUMO) ligases that mediates the attachment of a SUMO protein to proteins involved in nuclear transport, transcription, chromosome segregation and DNA repair. The encoded protein is part of the structural maintenance of chromosomes (SMC) 5/6 complex which plays a key role genome maintenance, facilitating chromosome segregation and suppressing mitotic recombination. A knockout of the orthologous mouse gene is lethal prior to embryonic day 10.5. Naturally occurring mutations in this gene, that abolish the SUMO ligase activity, are associated with primordial dwarfism and extreme insulin resistance.?