BPNT1 (3'(2'), 5'-bisphosphate nucleotidase 1) is a phosphatase enzyme that catalyzes the hydrolysis of 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP, preventing toxic PAP accumulation that inhibits sulfotransferases and RNA processing enzymes 1. The enzyme also hydrolyzes inositol 1,4-bisphosphate and plays roles in inositol recycling and phosphoinositide metabolism 2. BPNT1 localizes to the cytosol and is part of a conserved family of lithium-sensitive phosphatases 3. Mechanistically, BPNT1 functions in sulfur assimilation regulation and nucleotide metabolism homeostasis 4. Recent evidence reveals BPNT1 involvement in mammalian rapid tRNA decay (mRTD) pathways for quality control under heat stress, via intracellular pAp level control 5. Clinically, BPNT1 deficiency causes severe liver pathologies including hypoproteinemia, hepatocellular damage, edema, and impaired translation 1. Loss of BPNT1 also produces iron-deficiency anemia and anasarca, though these phenotypes can be rescued through dietary methionine restriction or HIF-2α overexpression 4. Conversely, BPNT1 overexpression promotes triple-negative breast cancer progression and docetaxel resistance through STUB1-mediated LIMA1 degradation 6. BPNT1 downregulation protects lens epithelial cells from UV-induced apoptosis, with therapeutic implications for age-related cataract 78.