Ndfip1 and Ndfip2 inhibit DMT1 transport activity. (A) Representative traces obtained in the fluorescence quenching assay used to determine DMT1 transport activity. A total of 100 μM CoCl2 (final concentration) was added to the cells (indicated by the arrow), and the rate of fluorescence quenching (slope of line in shaded area) was calculated as a measure of the activity of DMT1 at the plasma membrane. (B) The relative transport activity of DMT1 when Ndfip1 and Ndfip2 are ectopically expressed as measured using the fluorescence quenching assay as described in panel A. *Significant difference between transfected and control CHO-DMT1-II cells (P < .05). □ indicates CHO cells not expressing DMT1; ■, CHO-DMT1-II cells. Data are mean plus or minus SEM. (C) RT-PCR showing levels of Ndfip1 and Ndfip2 transcript after knockdown.
