Terms in this set (18)
which storage form of for iron is most soluble?
ferritin. because it is soluble, the iron is more readily available.
each ferritin binds 4500 ferrous atoms.
at steady state it is a good reflection of body stores.
soluble derivative of apoferritin.
apoferritin+Fe --> ferritin
insoluble derivative of ferritin -- aggregated ferritin.
turnover is slower.
can bind two ferric ions at any time. ferric = +3 charge.
about 1/3 of transferrin pool is usually saturated.
transferrin bound to Fe is constantly being turned over/releasing its iron to tissues.
iron in fe+2 form. from animals, poultry. it is better absorbed because in ferrous form. 30% absoprtion.
from plant food, enriched foods. only about 10% absorbed. comes in ferric form (+3 charge). not easily absorbed - need acidic environments for enhanced absorption.
which proteins are responsible for moving iron from intestines or macrophages into circulation?
ferroportin, hephaestin, ceruloplasmin.
which proteins have a role in how iron is regulated? e.g. absorption and release from macrophages.
HFE, hepcidin, hemojevulin
generated in the liver. polypeptide. produced due to inflammation and increase iron stores (iron overload). it binds to ferroportin to decrease release of iron.
there is downregulation of hepcidin in hypoxia (want to see more iron release).
what does the HFE gene do?
present in crypt cells - controls and gives signals to villous to absorb iron.
in tissue macrophages.
in kupffer cels.
what happens if HFE is mutated?
enhances ability of iron absorption = iron overload.
what iron form binds transferrin?
how is iron transported out of macrophages and intestinal cells?
what happens before iron can be transported out of macrophages and intestinal cells?
the iron must be converted from +2-->+3 by cerruloplasmin in macrophages and hephaestin in intestines.
how is non-heme absorbed in the gut?
it must be converted from +3-->+2 via cytochrome b. while in intestinal cell, remains in +2 form.
what happens with iron response proteins in the iron deficient state?
IRP1 becomes highly active and there is less IRP2 destruction. the IRP1 binds response element of ferritin and inhibits its production. therefore, there will be less storage ferritin formed. transferrin mRNA is enhanced (IRP2?). more iron goes into synthesis of hemoglobin (less sits in stores)
what happens with iron response proteins in the abundant cellular iron state?
IRP1 - has a low affinity for iron response elements. IRP2 is now degraded. results in translation of ferritin mRNA (more iron storage). and transferrin MRNA is degraded, need less hgb synthesis and more storage.
what is the main cause of microcytic anemia?