Appears to have dual functions such as cytoplasmic retention of attached NF-kappa-B proteins and generation of p52 by a cotranslational processing. The proteasome-mediated process ensures the production of both p52 and p100 and preserves their independent function. p52 binds to the kappa-B consensus sequence 5'-GGRNNYYCC-3', located in the enhancer region of genes involved in immune response and acute phase reactions. In concert with RELB, may play a role in the regulation of the circadian clock (By similarity). Active NF-kappa-B is a heterodimer of an about 52 kDa DNA-binding subunit and the weak DNA-binding subunit p65. Two heterodimers might form a labile tetramer (By similarity). Nuclear, but also found in the cytoplasm in an inactive form complexed to an inhibitor (I-kappa-B). Expressed in spleen. The C-terminus of p100 might be involved in cytoplasmic retention, inhibition of DNA-binding by p52 homodimers, and/or transcription activation. The glycine-rich region (GRR) appears to be a critical element in the generation of p52. While translation occurs, the particular unfolded structure after the GRR repeat promotes the generation of p52 making it an acceptable substrate for the proteasome. This process is known as cotranslational processing. The processed form is active and the unprocessed form acts as an inhibitor (I kappa B-like), being able to form cytosolic complexes with NF-kappa B, trapping it in the cytoplasm. Complete folding of the region downstream of the GRR repeat precludes processing (By similarity). Constitutive processing is tightly suppressed by its C-terminal processing inhibitory domain, named PID, which contains the death domain.