Negative Regulator Of Ubiquitin Like Protein 1 (NUB1)

NUB1 interacts with and negatively regulates NEDD8, a ubiquitin-like protein that covalently conjugates to cullin family members. The deduced 601-amino acid protein has a calculated molecular mass of about 69 kD. The N-terminal half of NUB1 contains 2 coiled-coil domains, and the C-terminal half contains 2 ubiquitin-associated domains, which are separated by a bipartite nuclear localization signal, followed by a PEST sequence. Northern blot analysis detected strong expression of a 2.3-kb transcript in testis and weak expression of a 3.5-kb transcript in testis, ovary, heart, and skeletal muscle. Little to no expression was detected in other tissues. Western blot analysis detected NUB1 at an apparent molecular mass of 69 kD expressed in all cell lines tested, with variable expression between cell lines.