LALBA(lactalbumin, alpha or alpha-lactalbumin) is a protein that in humans is encoded by the LALBA gene. The LALBA gene is mapped on 12q13.11. alpha-Lactalbumin is an important whey protein in cow's milk (~1 g/l), and is also present in the milk of many other mammalian species. In primates, alpha-lactalbumin expression is upregulated in response to the hormone prolactin and increases the production of lactose. alpha-Lactalbumin forms the regulatory subunit of the lactose synthase (LS) heterodimer and beta-1, 4-galactosyltransferase (beta4Gal-T1) forms the catalytic component. Together, these proteins enable LS to produce lactose by transferring galactose moieties to glucose. As a multimer, alpha-lactalbumin strongly binds calcium and zinc ions and may possess bactericidal or antitumor activity. A folding variant of human alpha-lactalbumin that may form in acidic environments such as the stomach, called HAMLET, probably induces apoptosis in tumor and immature cells.