Binds to specific AU-rich elements (ARE) in the 3'-untranslated region of target mRNAs and promotes their degradation. In response to iron deficiency, promotes the decay of many mRNAs encoding proteins involved in iron-dependent pathways. Negatively regulates primarily iron-dependent mitochondrial processes including respiration and amino acid biosynthesis. By transcription factors AFT1 and AFT2 in response to iron deficiency.