Ubiquitin-like molecules (UBLs), such as SUMO1 (UBL1; MIM 601912), are structurally related to ubiquitin (MIM 191339);and can be ligated to target proteins in a similar manner as ubiquitin. However, covalent attachment of UBLs does not;result in degradation of the modified proteins. SUMO1 modification is implicated in the targeting of RANGAP1 (MIM;602362) to the nuclear pore complex, as well as in stabilization of I-kappa-B-alpha (NFKBIA; MIM 164008) from;degradation by the 26S proteasome. Like ubiquitin, UBLs are synthesized as precursor proteins, with 1 or more amino;acids following the C-terminal glycine-glycine residues of the mature UBL protein. Thus, the tail sequences of the UBL;precursors need to be removed by UBL-specific proteases, such as SENP6, prior to their conjugation to target proteins;(Kim et al., 2000 (PubMed 10799485)). SENPs also display isopeptidase activity for deconjugation of SUMO-conjugated;substrates (Lima and Reverter, 2008 (PubMed 18799455)).