Biosynthesis of milk protein

• The primary proteins in milk are casein β casein κ casein α lactalbumin β lactalbumin.
• Milk proteins are synthesized from free amino acids most of which are derived through the blood supply.
• A second group of milk proteins, which includes the immune globulins, blood serum albumin, and the γ casein complex, appears to be composed of blood proteins that enter the mammary cell and appear unchanged in milk.
• Synthesis of these proteins from amino acids within the mammary cell is not required.