Serine palmitoyltransferase (SPT), which consists of two different subunits, is the key enzyme in sphingolipid biosynthesis. It converts L-serine and palmitoyl-CoA to 3-oxosphinganine with pyridoxal 5'-phosphate as a cofactor. SPT2 is the long chain base subunit 2 of mammalian serine palmitoyltransferase. SPT2 is catalytically active but needs its related protein SPT1 for its stabilization and anchoring the holoenzyme to the cytosolic face of the endoplasmic reticulum. As in the case with SPT1, mutations in the SPT2 gene can cause hereditary sensory and autonomic neuropathy type I (HSAN-I), resulting from a loss of SPT activity as well as the accumulation of the atypical and neurotoxic sphingoid metabolite 1-deoxy-sphinganine.