Human melanotransferrin (p97) has only one functional iron‐binding site

Abstract
The iron‐binding properties of melanotransferrin, the tumour‐associated antigen also known as p97, have been investigated by UV/visible and fluorescence spectroscopy, amino acid sequence comparison, and modelling. These show that, in contrast to other transferrins, melanotransferrin binds only one Fe3+ ion per molecule. The binding properties of its N‐terminal site are similar to other transferrins, but its C‐terminal site does not bind iron at all. The differences can be related to specific amino acid changes in the C‐terminal site.