<Tr> <Th> SO </Th> <Td> 0000233 </Td> </Tr> <Tr> <Th> PDB structures </Th> <Td> PDBe </Td> </Tr> <P> In molecular biology, the iron response element or iron - responsive element (IRE) is a short conserved stem - loop which is bound by iron response proteins (IRPs, also named IRE - BP or IRBP). The IRE is found in UTRs (untranslated regions) of various mRNAs whose products are involved in iron metabolism . For example, the mRNA of ferritin (an iron storage protein) contains one IRE in its 5' UTR . When iron concentration is low, IRPs bind the IRE in the ferritin mRNA and cause reduced translation rates . In contrast, binding to multiple IREs in the 3' UTR of the transferrin receptor (involved in iron acquisition) leads to increased mRNA stability . </P> <P> The two leading theories describe how iron probably interacts to impact posttranslational control of transcription . The classical theory suggests that IRPs, in the absence of iron, bind avidly to the mRNA IRE . When Iron is present, it interacts with the protein to cause it to release the mRNA . For example, In high iron conditions in humans, IRP1 binds with an iron - sulphur complex (4Fe - 4S) and adopts an aconitase conformation unsuitable for IRE binding . In contrast, IRP2 is degraded in high iron conditions . There is variation in affinity between different IREs and different IRPs . Some IREs can also be affected by alternative gene splicing . In the second theory, There are two proteins competing for the IRE binding site--both IRP and eukaryotic Initiation Factor F4 (eIFF4). In the absence of iron IRP binds about 10 times more avidly than the initiation factor . However, when Iron interacts at the IRE, it causes the mRNA to change its shape, thus favoring the binding of the eIFF4 . Several studies have identified non-canonical IREs . It has also been shown that IRP binds to some IREs better than others . </P>

Where is the ire located in the ferritin gene