Abstract
Iron absorption is known to be higher from human milk than from infant formula or bovine milk. The high bioavailability of human milk iron suggests that lactoferrin (Lf), the major iron-binding protein in human milk, may be a factor contributing to iron absorption in infants. We have isolated a human Lf receptor from solubilized human fetal intestinal brush-border membranes by affinity chromatography using immobilized human Lf. We also investigated the interaction of 125I-labeled human Lf and bovine Lf with brush-border membrane vesicles (BBMVs) from human small intestine using a rapid filtration technique. The molecular weight of the receptor was 110,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions and 37,000 under reducing conditions. Competitive binding studies demonstrated specific binding of human Lf. The binding was pH dependent, with an optimum between pH 6.5 and 7.5. Scatchard plot analysis indicated 4.3 x 1014 binding sites/mg membrane protein with an affinity constant of 0.3 x 106 M-1 for human Lf. Both half-Lf and deglycosylated Lf bound to the receptor with an affinity similar to intact Lf. In contrast, little binding of bovine Lf or human transferrin to human BBMVs occurred. These results suggest that the brush-border membrane receptor for human Lf may be responsible for the high iron absorption from human milk.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Gastrointestinal and Liver Physiology |
| Volume | 261 |
| Issue number | 5 24-5 |
| State | Published - 1991 |
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Keywords
- Intestinal absorption
- Iron absorption
- Lactoferrin receptor
ASJC Scopus subject areas
- Physiology
- Gastroenterology
Cite this
Isolation and function of a receptor for human lactoferrin in human fetal intestinal brush-border membranes. / Kawakami, H.; Lonnerdal, B.
In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 261, No. 5 24-5, 1991.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Isolation and function of a receptor for human lactoferrin in human fetal intestinal brush-border membranes
AU - Kawakami, H.
AU - Lonnerdal, B.
PY - 1991
Y1 - 1991
N2 - Iron absorption is known to be higher from human milk than from infant formula or bovine milk. The high bioavailability of human milk iron suggests that lactoferrin (Lf), the major iron-binding protein in human milk, may be a factor contributing to iron absorption in infants. We have isolated a human Lf receptor from solubilized human fetal intestinal brush-border membranes by affinity chromatography using immobilized human Lf. We also investigated the interaction of 125I-labeled human Lf and bovine Lf with brush-border membrane vesicles (BBMVs) from human small intestine using a rapid filtration technique. The molecular weight of the receptor was 110,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions and 37,000 under reducing conditions. Competitive binding studies demonstrated specific binding of human Lf. The binding was pH dependent, with an optimum between pH 6.5 and 7.5. Scatchard plot analysis indicated 4.3 x 1014 binding sites/mg membrane protein with an affinity constant of 0.3 x 106 M-1 for human Lf. Both half-Lf and deglycosylated Lf bound to the receptor with an affinity similar to intact Lf. In contrast, little binding of bovine Lf or human transferrin to human BBMVs occurred. These results suggest that the brush-border membrane receptor for human Lf may be responsible for the high iron absorption from human milk.
AB - Iron absorption is known to be higher from human milk than from infant formula or bovine milk. The high bioavailability of human milk iron suggests that lactoferrin (Lf), the major iron-binding protein in human milk, may be a factor contributing to iron absorption in infants. We have isolated a human Lf receptor from solubilized human fetal intestinal brush-border membranes by affinity chromatography using immobilized human Lf. We also investigated the interaction of 125I-labeled human Lf and bovine Lf with brush-border membrane vesicles (BBMVs) from human small intestine using a rapid filtration technique. The molecular weight of the receptor was 110,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions and 37,000 under reducing conditions. Competitive binding studies demonstrated specific binding of human Lf. The binding was pH dependent, with an optimum between pH 6.5 and 7.5. Scatchard plot analysis indicated 4.3 x 1014 binding sites/mg membrane protein with an affinity constant of 0.3 x 106 M-1 for human Lf. Both half-Lf and deglycosylated Lf bound to the receptor with an affinity similar to intact Lf. In contrast, little binding of bovine Lf or human transferrin to human BBMVs occurred. These results suggest that the brush-border membrane receptor for human Lf may be responsible for the high iron absorption from human milk.
KW - Intestinal absorption
KW - Iron absorption
KW - Lactoferrin receptor
UR - http://www.scopus.com/inward/record.url?scp=0026331372&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026331372&partnerID=8YFLogxK
M3 - Article
C2 - 1659221
AN - SCOPUS:0026331372
VL - 261
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 5 24-5
ER -