The interaction that facilitates lactose biosynthesis consists of a-lactalbumin (the regulatory unit) binding reversibly to the glycosyltransferase.

[1] N-acetyllactosamine synthase falls under the category of beta-1,4-galactosyltransferase, a type-II membrane protein found in the Golgi.

[2][3] Alpha-lactalbumin is a Ca2+ binding protein specific to mammary glands.

The Trp residue in the small loop moves allowing for the sugar nucleotide to be locked into the binding site.

This causes a conformational change in the large loop which then creates sites for oligosaccharide and metal ion binding, and protein-protein interactions for alpha-lactalbumin.