Multifunctional crystallin endowed with unrelated mRNA stabilization and enzymatic oxidoreductase activities (PubMed:17497241, PubMed:20103721). Binds (AU)-rich elements (ARE) in the 3'-UTR of target mRNA to enhance their stability (PubMed:17497241, PubMed:20103721). Upon metabolic acidosis, stabilizes the mRNA encoding SLC12A1 a cotransporter involved in transepithelial NH4(+) reabsorption in the medullary thick ascending limb in kidney (By similarity). In response to acidosis, also participates to the adaptive increase in renal ammoniagenesis by stabilizing the mRNAs of enzymes involved in glutamine catabolism (By similarity). By the same mechanism, it also regulates the expression of the antiapoptotic protein BCL2 (PubMed:20103721). Beside its mRNA stabilization activity, also catalyzes the reduction of orthoquinones such as 1,2-naphthoquinone or 9,10-phenanthrenequinone in the presence of NADPH in vitro and could be involved in the detoxification of xenobiotics and protection against oxidative stress (PubMed:17497241). {ECO:0000250|UniProtKB:P47199, ECO:0000250|UniProtKB:Q6AYT0, ECO:0000269|PubMed:17497241, ECO:0000269|PubMed:20103721}. This is the function of CRYZ (crystallin zeta, Ensembl gene identifier ENSG00000116791).