This family contains a number of ubiquitin-like proteins: SUMO (smt3 homologue) (see Swiss:Q02724), Nedd8 (see Swiss:P29595), Elongin B (see Swiss:Q15370), Rub1 (see Swiss:Q9SHE7), and Parkin (see Swiss:O60260). A number of them are thought to carry a distinctive five-residue motif termed the proteasome-interacting motif (PIM), which may have a biologically significant role in protein delivery to proteasomes and recruitment of proteasomes to transcription sites [5].

1: Structure of ubiquitin refined at 1.8 A resolution. Vijay-Kumar S, Bugg CE, Cook WJ; J Mol Biol 1987;194:531-544. PMID:3041007

2: Structure of tetraubiquitin shows how multiubiquitin chains can be formed. Cook WJ, Jeffrey LC, Kasperek E, Pickart CM; J Mol Biol 1994;236:601-609. PMID:8107144

3: Structure determination of the small ubiquitin-related modifier SUMO-1. Bayer P, Arndt A, Metzger S, Mahajan R, Melchior F, Jaenicke R, Becker J; J Mol Biol 1998;280:275-286. PMID:9654451

4: Crystal structure of the human ubiquitin-like protein NEDD8 and interactions with ubiquitin pathway enzymes. Whitby FG, Xia G, Pickart CM, Hill CP; J Biol Chem 1998;273:34983-34991. PMID:9857030

5: A potential proteasome-interacting motif within the ubiquitin-like domain of parkin and other proteins. Upadhya SC, Hegde AN; Trends Biochem Sci 2003;28:280-283. PMID:12826399