Background
The protein encoded by this gene belongs to the antizyme inhibitor family, which plays a role
in cell growth and proliferation by maintaining polyamine homeostasis within the cell.
Antizyme inhibitors are homologs of ornithine decarboxylase (ODC, the key enzyme in
polyamine biosynthesis) that have lost the ability to decarboxylase ornithine; however,
retain the ability to bind to antizymes. Antizymes negatively regulate intracellular polyamine
levels by binding to ODC and targeting it for degradation, as well as by inhibiting polyamine
uptake. Antizyme inhibitors function as positive regulators of polyamine levels by
sequestering antizymes and neutralizing their effect. This gene encodes antizyme inhibitor
1, the first member of this gene family that is ubiquitously expressed, and is localized in the
nucleus and cytoplasm. Overexpression of antizyme inhibitor 1 gene has been associated
with increased proliferation, cellular transformation and tumorigenesis. Gene knockout
studies showed that homozygous mutant mice lacking functional antizyme inhibitor 1 gene
died at birth with abnormal liver morphology. RNA editing of this gene, predominantly in the
liver tissue, has been linked to the progression of hepatocellular carcinoma. Alternatively
spliced transcript variants have been described for this gene.
