NEDD8 is a ubiquitin-like protein that controls vital biological events through its conjugation to cullin proteins. NEDD8 ultimate buster-1 (NUB1), is a negative regulator of the NEDD8 system that recruits NEDD8 and its conjugates to the proteasome for degradation. It is, therefore a cell growth regulator. The UBA domain of NUB1 is the specific acceptor for the linear ubiquitin precursor. NUB1 is composed of 601 amino acids. It is an interferon-inducible protein and predominantly localizes in the nucleus. NUB1 is specifically expressed in adult human testis, ovary, heart, and skeletal muscle tissues.