When the intracellular iron concentration is low, iron-scavenging molecules called ________ are produced
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Although essential, iron is also potentially toxic. It is maintained at optimal levels in mammalian cells by the actions of three proteins. Transferrin binds to extracellular iron ions and carries it within the bloodstream; the transferrin receptor binds iron-loaded transferrin and brings it into the cell; and ferritin binds iron within the cell to provide an intracellular storage site. Both ferritin and the transferrin receptor are regulated by mechanisms that are similar and complementary. a. Do a bit of research and describe in general how the concentrations of ferritin and transferrin receptor are regulated by iron levels. b. You will (hopefully) find that the two are regulated by a similar mechanism, but in an opposite fashion. Explain how this opposite regulation in response to iron levels makes biological sense.
Madhur L.
Iron is a vital yet potentially toxic substance. How are optimum levels of iron maintained in mammalian cells. An iron binding protein known as iron regulatory protein (IRP) plays a key role in this regard. Which of the following statements about iron regulatory protein (IRP) is not true? when iron is limiting the IRP binds to iron response element (IRE) in the 3' UTR of the transferrin receptor mRNA and inhibits translation when iron is limiting IRP binds to the iron response element (IRE) in the 5' UTR of the ferritin mRNA and inhibits translation. when iron is in excess, it binds to IRP and prevents it from binding to iron response element (IRE) of ferritin and promotes translation. Thus, more ferritin is made when iron is high.
After a search of nucleotide sequence databases, researchers identified an IRE in the 5' untranslated region of a gene encoding aconitase, an enzyme involved in the Krebs cycle. Which of the following pieces of experimental evidence best supports the claim that the synthesis of aconitase is controlled by a mechanism similar to ferritin regulation? (A) IRP binds to aconitase mRNA in the presence of iron. (B) The relative amount of aconitase protein increases in the presence of high levels of iron. (C) Oxygen consumption by cells increases in the presence of high levels of iron. (D) The levels of reduced electron carriers, NADH and FADH2, increase in the presence of high levels of iron.
Lochan U.
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