Protein which is posttranslationally modified by the attachment of at least one ubiquitin-like modifier protein, such as ubiquitin, SUMO, APG12, URM1 or RUB1. Ubiquitin, for example, is linked through a thioester bond between its C-terminus and the epsilon group of a lysine residue present on either another ubiquitin-like modifier protein or a target protein.
