Lactoferrin receptors in intestinal brush border membranes

Area of Science:

• Biochemistry
• Gastroenterology
• Neonatal Physiology

Background:

• Lactoferrin, a milk protein, may influence neonatal iron absorption and gut development.
• A specific receptor on enterocytes is hypothesized to mediate lactoferrin's physiological effects.

Purpose of the Study:

• To investigate the presence and characteristics of lactoferrin receptors in the intestinal brush border membrane of infant rhesus monkeys and human fetuses/infants.
• To determine the specificity, binding kinetics, and molecular properties of the lactoferrin receptor.

Main Methods:

• Studied lactoferrin receptor binding in brush border membranes from infant rhesus monkey and human intestines.
• Utilized saturation kinetics, specificity assays, enzymatic deglycosylation, and competitive binding experiments.
• Isolated and characterized the human lactoferrin receptor.

Main Results:

• Identified specific lactoferrin receptors on the intestinal brush border.
• Demonstrated specific binding for human and monkey lactoferrin, but not bovine lactoferrin or human transferrin.
• Found that glycosylation is not essential for binding, and holo-lactoferrin binds more effectively.
• Isolated a 110 kDa human lactoferrin receptor, which has been cloned and sequenced.

Conclusions:

• A specific lactoferrin receptor exists on the enterocyte brush border membrane in primates.
• This receptor plays a role in mediating lactoferrin's effects on the neonatal intestine.
• The receptor's characteristics suggest a role in nutrient absorption and mucosal health.