試題詳解

7. Cellular iron homeostasis is accomplished by the coordinated regulated expression of the transferrin receptor and ferritin, which mediate iron uptake and storage, respectively. There are iron responsive element (IRE) in the 5' UTR of ferritin mRNA and in the3' UTR of transferrin receptor mRNA.

(1) IRE-binding proteins bind to IREs of ferritin mRNA to inhibit translation in lower iron concentration； 

(2) IRE-binding proteins bind to IREs of ferritin mRNA to inhibit translation in higher iron concentration；

(3) IRE-binding proteins bind to IREs of transferrin receptor mRNA to stabilize mRNA in lower iron concentration；

(4) IRE-binding proteins bind to IREs of transferrin receptor mRNA to stabilize mRNA in higher iron concentration. Which are correct?
(A) (1) and (3)
(B) (2) and (4)
(C) (1) and (4)
(D) (2) and (4)
(E) all are incorrect