Functional Roles of Ubiquitin-Like Domain (ULD) and Ubiquitin-Binding Domain (UBD) Containing Proteins

The functional roles of ubiquitin-like domain (ULD) and ubiquitin-binding domain (UBD) containing proteins, in the regulation of various cellular activities and etiology of human diseases, are presented. Ubiquitin-like folds are recognized as important integral elements of proteins, forming ubiquitin-like domains (ULDs), which are present in a large variety of protein families. New proteins with alternative ULD/UBD combinations are being identified, including the UBX/UBA proteins primarily functioning in the ERAD pathway and SLD/SIM proteins. Ubiquitin conjugation targets protein substrates for degradation by the proteasome and influences a broad repertoire of cellular processes. The activity of ULD/UBA family members are important for the regulation of proteins including cell-cycle regulators, oncogenes, and tumor suppressors. Targeting nonenzymatic proteins such as ULD/UBDs comprise a group of highly interesting therapeutic targets for cancer therapy.