The function of ME1 (malic enzyme 1, ENSG00000065833) is as follows. Catalyzes the oxidative decarboxylation of (S)-malate in the presence of NADP(+) and divalent metal ions, and decarboxylation of oxaloacetate. {ECO:0000269|PubMed:7622060, ECO:0000269|PubMed:7757881, ECO:0000269|PubMed:8187880, ECO:0000269|PubMed:8804575}.