Curr. Issues Mol. Biol. (2020) 35: 99-108. Role of Ubiquitin and SUMO in Intracellular Trafcking Maria Sundvall1,2,3* 1Institute of Biomedicine, University of Turku, Turku, Finland. 2Western Cancer Centre FICAN West, Turku University Hospital, Turku, Finland. 3Department of Oncology and Radiotherapy, University of Turku, Turku, Finland. *Correspondence:
[email protected] htps://doi.org/10.21775/cimb.035.099 Abstract behaviour. In addition to e.g. chemical groups, Precise location of proteins at a given time within such as phosphate groups, proteins can be modi- a cell is essential to convey specifc signals and fed by small polypeptides, such as ubiquitin and result in a relevant functional outcome. Small SUMO. Ubiquitin and SUMO share a similar ubiquitin-like modifcations, such as ubiquitin three-dimensional structure and are principally and SUMO, represent a delicate and diverse way covalently linked at lysine (K) residues of sub- to transiently regulate intracellular trafcking strate proteins by a similar conjugation pathway events of existing proteins in cells. Trafcking (Hershko et al., 1998; Hay, 2013). Unlike ubiq- of multiple proteins is controlled reversibly by uitin, SUMO is preferentially atached at SUMO ubiquitin and/or SUMO directly or indirectly via consensus sites ΨKxE in substrates Ψ = hydropho- regulation of transport machinery components. bic residue with high preference for I or V, x = any Regulation is dynamic and multilayered, involv- amino acid) under steady state conditions, but ing active crosstalk and interdependence between under stress conditions in particular more non- post-translational modifcations. However, in consensus sites are SUMOylated (Hendriks et al., most cases regulation appears very complex, and 2016).