Disorder in Milk Proteins: Lactadherin Multifunctionality and Structure

Milk fat globule membrane (MFGM) is one of the milk components that is produced by the lactating mammary glands and released to the milk in the form of vesicles. MFGM surrounds milk fat globule secreted by the milk producing cells and has a complex structure containing various lipids (e.g., triacylglycerides, phospholipids, and cholesterol), proteins and other macromolecules. Among the proteinaceous components of MFGM is lactadherin, also known as milk fat globule-EGF factor 8 protein (MFG-E8). Being one of the main proteins present in MFGM, lactadherin is related to milk secretion, has antimicrobial and antiviral effects, and plays important roles in the immune defense as one of the immune system molecules. Furthermore, lactadherin belongs to the family of secreted extracellular matrix proteins, and clearly can be considered as a multifunctional (or moonlighting) glycoprotein involved in regulation of many biological and physiological processes, such as angiogenesis, atherosclerosis, haemostasis, phagocytosis, and tissue remodeling. This review focuses on the similarities and differences of lactadherin among different species and describes the main functions of this protein, as well as its structure.