Role of melanotransferrin (p97) in non-transferrin iron uptake by HeLa andK562 cells

We tested whether melanotransferrin (p97), an iron-binding protein of the p lasma membrane, is involved in the transport of non-transferrin iron into h uman HeLa and K562 cells. The expression of melanotransferrin was detected in HeLa but not in K562 cells. PI-PLC treatment dramatically decreased (to 20% of the original value) p97 expression by HeLa cells. However, the rate of iron uptake from Fe-55-ferric citrate by PI-PLC-treated HeLa cells was c omparable or only slightly lower (80-100%) than the rate of iron uptake by untreated cells. PI-PLC treatment had no effect on iron uptake by K562 cell s. These findings strongly support the suggestion that melanotransferrin do es not play a substantial role in non-transferrin iron uptake by either HeL a or K562 cells.