Specific binding of lactoferrin to brush-border membrane: ontogeny and effect of glycan chain.
Bioavailability of iron from human milk is exceptionally high. It has been suggested that lactoferrin, the major iron-binding protein in human milk, may participate in this high iron bioavailability from milk. We examined the interaction of lactoferrin with the intestinal brush-border membrane using the rhesus monkey as a model. Brush-border membrane vesicles were prepared from monkeys of various ages. Binding studies with 59Fe-labeled human and monkey lactoferrin were performed to examine interaction of lactoferrin with the brush-border membrane. Specific saturable binding of lactoferrin was found at all ages studied (fetal, suckling infant, weaned infant, juvenile, and adult). The dissociation constant for lactoferrin-receptor binding was 9 X 10(-6) M. In contrast, no binding of serum transferrin or bovine lactoferrin occurred. Removal of fucose from the lactoferrin glycans resulted in a significant decrease in binding. It was concluded that lactoferrin in milk may function in the process of iron absorption through interaction with a small intestinal receptor and that fucosylated glycans on the carbohydrate chain of lactoferrin are necessary for receptor recognition.
Davidson
L A
LA
Department of Nutrition, University of California, Davis 95616.
Lönnerdal
B
B
D000375:Aging; D000818:Animals; D005333:Fetus; D006801:Humans; D007583:Jejunum / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism; D007700:Kinetics; D007781:Lactoferrin / Q000378:metabolism*; D007782:Lactoglobulins / Q000378:metabolism*; D008253:Macaca mulatta; D008871:Microvilli / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*
D007782:Lactoglobulins; D011956:Receptors, Cell Surface; C038340:lactoferrin receptors; D007781:Lactoferrin