Expression of DMT1 protein in the gastrointestinal tract of anemic mk/mk mice.

Proximal (I1) and distal (I2) sections of the duodenum as well as ileum (I3) and colon (C) were harvested from heterozygous mk/+(lanes 3, 5, 7, and 9) or homozygous mk/mk mice (lanes 4, 6, 8, and 10). Microsomal fractions were prepared as previously described11 and 80 μg samples of membrane proteins were resolved on a 10% acrylamide gel and transferred to a polyvinylidene fluoride membrane. For comparison, microsomal fractions isolated from proximal duodenum (I1) of wild type mice (+/+) fed a normal diet (lane 1) or a low-iron diet (lane 2) were included in the analysis. To demonstrate the specificity of the anti-DMT1 antibody, 5 μg of membrane proteins from CHO cells (lane 11) or CHO cells expressing cMyc-tagged DMT1 isoform II (lane 12) were also included. Immunoblotting was performed with antibodies raised against the amino terminus of DMT1 (DMT1-NT) (A), the transferrin receptor (B), and Bgp1 proteins (C). The positions and sizes (in kilodaltons) of molecular mass markers are indicated on the right.