Small ubiquitin-related modifier 1, 2 and 3 (SUMO-1, -2 and -3) are
members of the ubiquitin-like protein family . The covalent attachment of
the SUMO-1, -2 or -3 (SUMOylation) to target proteins is analogous to
ubiquitination. This post-translational modification is a reversible, multi
step process that is initiated by cleaving a precursor protein to a mature
protein. Mature SUMO-1, -2 or -3 is then linked to the activating enzyme
E1, conjugated to E2 and in conjunction with E3, SUMO-1, -2 or -3 is
ligated to the target protein . Ubiquitin and the individual SUMO family
members are all targeted to different proteins with diverse biological
functions. Ubiquitin predominantly regulates degradation of its target .
