Ornithine decarboxylase (ODC) antizyme protein that negatively regulates ODC activity and intracellular polyamine biosynthesis and uptake in response to increased intracellular polyamine levels. Binds to ODC monomers, inhibiting the assembly of the functional ODC homodimers. Does not target the ODC monomers for degradation, which allows a protein synthesis-independent restoration of ODC activity (PubMed:17900240). Involved in the translocation of AZIN2 from ER-Golgi intermediate compartment (ERGIC) to the cytosol (By similarity). {ECO:0000250|UniProtKB:O08608, ECO:0000269|PubMed:17900240}. This is the function of Ensembl gene identifier ENSG00000180304 (OAZ2, ornithine decarboxylase antizyme 2).