Serine palmitoyltransferase (SPT). The heterodimer formed with LCB2 constitutes the catalytic core (By similarity). H(+) + hexadecanoyl-CoA + L-serine = 3-oxosphinganine + CO2 + CoA Lipid metabolism; sphingolipid metabolism. Heterodimer with LCB2. Component of the serine palmitoyltransferase (SPT) complex, composed of LCB1 and LCB2 (By similarity). Belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family.