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. Recruits the DHH1 helicase to the SDH4 mRNA and promotes SDH4 mRNA decay. Also destabilizes target mRNA by modulating 3'-end processing, creating extended transcripts that are prone for degradation. Interacts with DHH1. By transcription factors AFT1 and AFT2 in response to iron deficiency.