NUTR SCI 332 Lecture Notes - Lecture 8: Transferrin Receptor, Transferrin, Ferroportin
Trace minerals
Iron
• Transports oxygen
• Most common nutrient deficiency in the world
• Homeostasis mostly controlled by absorption our ody does’t hae a
regulated way of excreting/releasing it from stores)
• Molecular mechanisms underlying the regulation
• Proteins that interact: ferrous (Fe2+) vs ferric (Fe3+) iron
• Proteins requiring iron to function
o Hemoglobin: carrier of oxygen, contains heme (made from
amino acids), ferrous iron ion sits in the middle
o Myoglobin: carries oxygen into muscle, contains heme group in
the middle to store some oxygen
o Iron-containing enzymes
• Iron transport proteins
o Transferrin: carries 3+ form
o Transferrin receptor: brings iron into cells
o Ferroportin: sits on plasma membrane for iron to go out of the
cell
• Iron storage protein: ferritin
• Functions of iron:
o Oxygen carrier: hemoglobin and myoglobin
o Metabolism
find more resources at oneclass.com
find more resources at oneclass.com
2
▪ Enzymes in the TCA cycle (needed for citrate → isocitrate
reaction in citric acid cycle)
▪ Cytochromes in electron transport chain
▪ Production of neurotransmitters
• Iron recycling: oe iro eters the ody, it a’t get out a oly get
lost by sweat, skin, urine, and blood)
o Transferrin sends iron to tissues to make proteins and RBCs
o Once those cells die, the iron gets recycled
o Liver (and spleen) dismantles iron from RBCs and packages or
stores it
• Bioavailability of heme vs. non-heme iron
o Only animal-based foods have heme, but they also contain non-
heme iron
o Heme only accounts for 10% of daily iron intake, but is better
absorbed (about 25%) than non-heme
• Iron absorption
find more resources at oneclass.com
find more resources at oneclass.com
3
o Iron in food goes into intestine
o Mucosal cells store excess iron in mucosal ferritin
o Liver regulates iron levels
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Iron transport proteins: transferrin: carries 3+ form, transferrin receptor: brings iron into cells, ferroportin: sits on plasma membrane for iron to go out of the cell. Iron storage protein: ferritin: functions of iron, oxygen carrier: hemoglobin and myoglobin, metabolism, enzymes in the tca cycle (needed for citrate isocitrate reaction in citric acid cycle, cytochromes in electron transport chain, production of neurotransmitters. 2: iron in food goes into intestine, mucosal cells store excess iron in mucosal ferritin, liver regulates iron levels. 3+ form (requires copper as a cofactor: iron picked up by liver, hepcidin shuts the ferroportin door (negative feedback for homeostasis, copper is a cofactor for absorption (help iron absorption) Iron requirements: pregnant women have highest, females > males, adolescent needs > adult needs (for men, postmenopausal women < women of child-bearing age (need more for menstruation, calcium interferes with iron absorption, vitamin c helps with iron absorption.
