ID 2.4.1.22 DE lactose synthase. AN N-acetyllactosamine synthase. AN UDP-galactose--glucose galactosyltransferase. CA D-glucose + UDP-alpha-D-galactose = H(+) + lactose + UDP. CC -!- The enzyme is a complex of 2 proteins A and B. CC -!- In the absence of the B protein (alpha-lactalbumin) the enzyme CC catalyzes the transfer of galactose from UDP-galactose to CC N-acetylglucosamine (cf. EC 2.4.1.90). DR P08037, B4GT1_BOVIN; P15291, B4GT1_HUMAN; P15535, B4GT1_MOUSE; DR P80225, B4GT1_RAT ; Q80WN9, B4GT2_CRIGR; O60909, B4GT2_HUMAN; DR Q9Z2Y2, B4GT2_MOUSE; //