ATP23 is a mitochondrial metallopeptidase with dual functions in ATP synthase biogenesis. Primarily, ATP23 processes the precursor form of ATP synthase subunit 6 (Atp6/subunit 6) by removing its targeting sequence 1. Beyond proteolytic processing, ATP23 functions as a chaperone facilitating assembly of the F(O) complex, coordinating with chaperone Atp10p to stabilize subunit 6 and enable its incorporation into the ATP synthase holoenzyme 12. The LRDK motif (residues 112-115) is critical for assembly function 2. ATP23 localizes to the mitochondrial inner membrane and is conserved across eukaryotes 13. In disease contexts, ATP23 expression patterns show clinical relevance: high ATP23 expression correlates with poor prognosis in glioblastoma 4, while reduced ATP23 in colorectal adenocarcinoma associates with immunosuppression through impaired T-cell oxidative phosphorylation and predicts worse outcomes 5. Additionally, ATP23 variants show association with red cell alloimmunization susceptibility in sickle cell disease patients 6. These findings indicate ATP23 functions beyond mitochondrial biogenesis as a potential prognostic biomarker in cancer and transfusion-related complications.