The SUMO proteins are a class of small ubiquitin-like modifiers. SUMO is attached to a specific lysine side chain on the target protein via an isopeptide bond with its C-terminal least fourSUMOproteins in humans, which are involved in protein trafficking and tar- geting. A truncated human SUMO-2 protein that contains residues 9–93 was expressed inEscherichia coliand crystal- lized in two different unit cells, with dimensions of a ¼b¼ A ˚ ,c¼ A ˚ and a¼b¼ A ˚ ,c¼ A ˚ , both belonging to the rhombohedral space groupR3. They diffractedX-rays A˚ A ˚ resolution, respectively
