Iron metabolism regulation mini-deck

Question 1

Transferrin

Answer 1

binds iron

Question 2

Transferrin Receptor (TFR)

Answer 2

transports transferrin/Fe into the cell

Question 3

Ferritin

Answer 3

sequesters excess Fe. Ferretin is a “shadow” of iron storage. Amt of ferretin parallels the iron reserves/stores.

Question 4

Iron Response Element (IRE). What is the crucial difference?

Answer 4

Sequence on mRNA of both ferretin and transferrin receptor.

On Transferrin Receptor mRNA, the IRE contains the cut site for degradative enzymes. Exposure of the site leads to degradatio.

On Ferretin, the IRE contains the initiation sequence. Exposure of the IRE allows translation of mRNA to proceed.

Question 5

Iron Response Binding Proteins (IRE-BPs) 1 & 2

Answer 5

bind Fe & regulate expression of ferritin and TFR.

Question 6

Transferrin receptor protein levels go ____ under low iron.

Answer 6

up

Question 7

Ferretin expression is ____ with high iron.

Answer 7

increased

Question 8

Under low iron, what happens to the Transferrin receptor mRNA?

Answer 8

Under low iron, transferrin is needed. IRE is bound and protected by the IRE-BP, and translation of the receptor proceeds.

Question 9

Under high iron, what happens to the Transferrin receptor mRNA?

Answer 9

Under high iron, the Transferrin receptor is not needed. Iron binds the IRE-BPs, inactivating them. IRE binding site is exposed, mRNA is degraded.

Question 10

Under low iron, what happens to the ferretin mRNA?

Answer 10

Under low iron, Ferretin is not needed. IRE is bound by IRE-BP. Expression of mRNA downregulated.

Question 11

Under high iron, what happens to the ferretin mRNA?

Answer 11

Under high iron, Ferretin is needed. IRE unbound by IRE-BP, expression of Ferretin upregulated.