Calorimetric studies of melanotransferrin (p97) and its interaction with iron.

The mammalian molecule melanotransferrin (mTf), also called p97, is a member of the transferrin family of molecules. It exists in both secreted and glycosylphosphatidylinositol-anchored forms and is thought to play a role in angiogenesis and in transporting iron across the blood brain barrier. The binding affinity of iron to this molecule has not been formally established.

Identification of a novel route of iron transcytosis across the mammalian blood-brain barrier.

Objective: This study was undertaken to assess the role of p97 (also known as melanotransferrin) in the transfer of iron into the brain, because the passage of most large molecules is limited by the presence of the blood-brain barrier, including that of the serum iron transporter transferrin.

Methods: To study the function of the soluble form of p97, we followed the uptake of radioiodinated and 55Fe loaded p97 and transferrin by the brain during a 24-hour period.

Results: We show that the soluble form of p97 has the ability to transcytose across the murine blood-brain barrier, and its transcytosis can be inhibited in a specific manner.