The particular arrangement of catalytic and regulatory subunits in this enzyme affords the complex with strongly allosteric behaviour with respect to its substrates.
The three-dimensional arrangement of the catalytic and regulatory subunits involves several ionic and hydrophobic stabilizing contacts between amino acid residues.
The regulatory subunits exist as hexamers, formed by the symmetrical assembly of 3 interlocked homodimers, creating an unusual 12-stranded beta-barrel structure.
Alpha-lactalbumin, is a milk protein that acts as the regulatory subunit of lactose synthetase, acting to promote the conversion of galactosyltransferase to lactose synthase, which is essential for milk production.