||Lactadherin is a widely distributed glycoprotein (~ 50 kDa), which was originally characterized due to its association with milk fat/lipid globule membranes. Synonymous names are PAS-6/7, bovine-associated mucoprotein, BA-46, P47, and MFG-E8. Structural hallmarks of lactadherin are the presence of two epidermal growth factor (EGF) homology domains (with an RGD peptide motif in the second EGF domain), and two C domains sharing homology with the discoidin family of lectin domains including the phospholipid-binding domains of blood clotting factors V and VIII. Lactadherin shows preferential binding to phosphatidylserine (L-form) in a calcium independent manner. Purified lactadherin functions as an anticoagulant by blocking phosphatidylserine-containing membrane sites for blood coagulation proteins. Fluoresence-labeled lactadherin functions as a sensitive probe for exposed phosphatidylserine on nucleated cells and on stimulated platelets. Lactadherin will bind to membranes that have phosphatidylserine content below the threshold for annexin V binding.