Catalyzes the synthesis of 5-aminolevulinate (ALA) from succinyl-CoA and glycine, the first and rate-limiting step in heme biosynthesis. glycine + H(+) + succinyl-CoA = 5-aminolevulinate + CO2 + CoA Ihnhibited by hemin. Optimum pH is 7.4. Porphyrin-containing compound metabolism; protoporphyrin-IX biosynthesis; 5-aminolevulinate from glycine: step 1/1. Homodimer (PubMed:6381051). Interacts with MCX1 (PubMed:25957689). In combination with a disruption of MCX1, abrogates mitochondrial respiration. Present with 22600 molecules/cell in log phase SD medium. Belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family.