Rabbit Anti-Human COPS5 polyclonal antibody for IHC-P. Jun activation domain-binding protein-1 (JAB1) also designated COP9 subunits 5 (COPS5) or SGN5 is a coactivator of AP-1 transcription factor that also promotes degradation of the cyclin-dependent kinase inhibitor p27Kip1. JAB1 interacts with c-Jun AP-1 containing complexes, and enhances transactivation from AP-1-dependent promoters. JAB1 is highly conserved in evolution and is widely expressed in mammalian tissues. It is localized both the nucleus and the cytoplasm.