Summary
Human lactoferrin (lactoferrin) has been shown to bind to receptors present in the human small intestine and on various other types of cells. Little is known about the structural features of the lactoferrin molecule that are needed for receptor recognition. The lactoferrin gene has been cloned and sequenced and recombinant lactoferrin has been expressed in baby hamster kidney cells. The recombinant lactoferrin has been shown to have normal iron-binding properties, but glycosylation of the recombinant lactoferrin appears to differ from that of the native lactoferrin. This expression system has also made it possible to use site-directed mutagenesis to produce variants of human lactoferrin. In this study, we analyze the physical characteristics as well as the receptor binding properties of recombinant lactoferrin and its structural variants, including the N-lobe, N-lobe treated with PNGase, and the N-lobe with its glycosylation site (N137A) mutated. Laser-induced desorption/ionization time-of-flight mass spectrometry is used to evaluate differences between the predicted and observed molecular mass values as a function of posttranslational modification. Competitive binding experiments are conducted with both native and recombinant human lactoferrin to assess receptor binding properties using human brush-border membranes. Each of the recombinant lactoferrin proteins competes effectively with native lactoferrin for receptor binding. The N-lobe alone appears to have a greater affinity for the binding sites than does the intact native lactoferrin. We conclude from these studies that the presence of glycans is not essential for receptor recognition and that the N-lobe of lactoferrin is both necessary and probably sufficient to allow normal binding to the receptor(s).
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Iyer, S. et al. (1997). Recombinant Human Lactoferrin and Its Variants. In: Hutchens, T.W., Lönnerdal, B. (eds) Lactoferrin. Experimental Biology and Medicine, vol 28. Humana Press. https://doi.org/10.1007/978-1-4612-3956-7_16
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DOI: https://doi.org/10.1007/978-1-4612-3956-7_16
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