Rabbit Anti-Human RBX1 polyclonal antibody for IHC-P. ROC1 and ROC2 are the two highly conserved RING finger proteins that are homologous to APC11, a subunit of the anaphase-promoting complex (APC) . ROC1 and ROC2 commonly interact with all cullins while APC11 specifically interacts with APC2, a cullin-related APC subunit. ROC1 and APC11 immunocomplexes can catalyze isopeptide ligations to form polyubiquitin chains in an E1- and E2-dependent manner. ROC1 is thought to play a unique role in the ubiquitination reaction by heterodimerizing with cullin1 to catalyze ubiquitin polymerization.