Figure 3.

(A) Structure of NOX4. NOX4 is comprised from six membrane-spanning alpha-helices (I–VI) connected by five loops (A–E) and an intracytoplasmic tail that contains binding sites for FAD (not shown) and NADPH. Two heme molecules (H in red box) are anchored to four histidine residues in helices III and V, allowing electron transport to oxygen molecules. H₂O₂ production takes place in the E loop. The protein p22 supports the stabilization of NOX4, while Poldip2 associates with p22 and contributes to the activation of NOX4 [92,93]. (B) NOX4 transcript variants [94]. Ex. = exon, the numbers refer to the numeration of exons. Empty box: exons present in the mRNA variant. Shaded boxes: missing exons from the mRNA variant. Triangle: early STOP codon.