Wingert et al. (2005) determined that the human GLRX5 gene encodes a 157-amino acid protein that is highly conserved among zebrafish, mouse, and human.Wingert et al. (2005) found high expression of Grx5 in developing blood and in liver and heart of zebrafish. In mice, Grx5 expression at embryonic day 7.5 (E7.5) was ubiquitous, but preferential expression in yolk sac blood islands was evident by E8.5. There was progressive downregulation of Grx5 in maturing primitive red cells between E10.5 and E12.5 and high expression in fetal liver at E12.5.Overexpression of ALAS2 RNA without the 5-prime iron response element that binds IRP1 rescued sir embryos, whereas overexpression of ALAS2, including the iron response element, did not. Further, antisense knockdown of IRP1 restored sir embryo hemoglobin synthesis.