description
Synthesis of the disaccharide lactose takes place within the Golgi apparatus of epithelial cells of the lactating mammary gland. The synthesis itself is a single chemical reaction of free glucose and UDP-galactose to form lactose and UDP. For this reaction to occur, glucose is transported from the cytosol into the Golgi lumen, and B4GALT1 interacts with LALBA (alpha-lactalbumin) to modulate its substrate specificity (Brew and Hill 1975)

external resources
NCBI:1269968
REACTOME:R-HSA-5653890
PUBMED:806951

genes
B4GALT1 , LALBA , SLC2A1 ,