PM20D2 is a cytosolic metallopeptidase that catalyzes peptide bond hydrolysis in dipeptides containing basic amino acids (lysine, ornithine, or arginine) at the C-terminus 1. The enzyme preferentially hydrolyzes β-alanyl-lysine, β-alanyl-ornithine, and γ-aminobutyryl-lysine, with lower activity on classic dipeptides like α-alanyl-lysine 1. PM20D2 functions as a metabolite repair enzyme that eliminates aberrant dipeptide byproducts generated during carnosine and homocarnosine synthesis, preventing accumulation of unwanted metabolites while favoring synthesis of physiologically important dipeptides 1. This housekeeping role ensures fidelity in amino acid metabolism pathways operating in skeletal muscle and brain. Clinically, PM20D2 shows dysregulation in disease contexts. The enzyme was identified as an upregulated protein in FASN-silenced osteosarcoma cells, suggesting involvement in tumor-associated metabolic reprogramming 2. Recent meta-analytic evidence indicates sex-specific differential expression of PM20D2 in subcutaneous adipose tissue of females with type 2 diabetes, linking it to metabolic disease pathophysiology and highlighting potential sex-based differences in metabolic regulation 3. These findings suggest PM20D2 participates in broader metabolic networks beyond carnosine synthesis, with potential implications for understanding metabolic diseases and tumor biology.