This gene encodes a bifunctional mitochondrial protein that catalyzes the first two steps in the lysine degradation pathway. The N-terminus contains lysine-ketoglutarate reductase activity and converts lysine to saccharopine, whereas the C-terminus contains saccharopine dehydrogenase activity and converts saccharopine to alpha-aminoadipate semialdehyde. Mutations in a human gene encoding a highly similar protein are associated with familial hyperlysinemia. [provided by RefSeq, Jul 2008]