Ubiquitin is a 77 amino acid protein that targets proteins for degradation by the 26S proteasome. Ubiquitin-like proteins are not directly involved in protein degradation, but appear to have many mechanistic similarities with the ubiquitin pathway. UBL3 (ubiquitin-like protein 3), also known as membrane-anchored ubiquitin-fold protein (MUB) or PNSC1, is a 117 amino acid membrane protein belonging to the ubiquitin-like family. Highly conserved between species, UBL3 contains two potential N-glycosylation sites, a potential protein kinase C phosphorylation site, and a potential C-terminal prenylation site. The gene encoding UBL3 is localized to chromosome 13q12.3.