Kappa-Casein (CSN3) is a secreted protein that belongs to the Kappa-Casein family. CSN3 exists in heteromultimers that are composed of alpha-s 1casein and kappa casein linked by disulfide bonds. CSN3 is involved in a number of important physiological processes. In the gut, CSN3 protein is split into an insoluble peptide (para kappa-casein) and a soluble hydrophilic glycopeptide (caseinomacropeptide). Caseinomacropeptide is responsible for increased efficiency of digestion, prevention of neonate hypersensitivity to ingested proteins, and inhibition of gastric pathogens. Kappa-casein also stabilizes micelle formation, preventing casein precipitation in milk.