Identification of an ENU-induced missense substitution in Steap3 in the fragile-red mouse mutant. (A) Peripheral blood erythrocyte indices from 8-week-old wild-type (WT; n = 8) and fragile-red homozygous mice (n = 7). Data show means and SDs. Statistical analysis was performed using unpaired t test to WT controls. (B) Representative peripheral blood film from wild-type and fragile-red. Bar = 10 μm. (C) 867T → C substitution in steap3 cDNA. (D) Sequence trace of bone marrow cDNA from a Steap3^Y288H/+ (steap3^HET) mouse. (E-G) Location of the mutation (starred) in the domain structure of Steap3 (E) in model (F), showing putative structure of the ferrireductase in endosomal membrane (central heme iron in red), and in amino acid sequence (G) between transmembrane domains 2 and 3.