A heterodimeric enzyme responsible for the synthesis of lactose from glucose and UDP-galactose. The catalytic A chain (EC 18.104.22.168) is derived from β-1,4-galactosyltransferase 1 (398 aa) by processing; the regulatory B subunit is α-*lactalbumin. The Golgi complex form catalyses the production of lactose in the lactating mammary gland. The cell surface form functions as a recognition molecule.
Subjects: Medicine and Health.