Fig. 4.

Schematic illustration of the structures of iron-responsive elements (IREs). The IREs are mRNA motifs of two general types: (1) those containing the consensus 3ꞌ-CAG(U/A)GN-5ꞌ sequence (typical (Type I) IRE motif); and (2) those with a modified sequence (atypical (Type II) IRE motif) that also bind IRPs. Typical IREs in the 5′ UTR are found in the mRNAs of: human ferritin-H chain, human ferroportin1, human mitochondrial aconitase (mACO), human HIF2α and human erythroid δ-aminolevulinic acid synthase (eALAS). Typical IREs in the 3′ UTR are found in transferrin receptor 1 and Dmt1 mRNAs. Atypical IREs have been identified in the 5ꞌ UTR of α-synuclein and amyloid precursor protein (APP). Two predicted atypical IRE structures of α-synuclein have been reported (prediction #1 was from Refs. [223,394] and prediction #2 was from Ref. [224].