Hephaestin Is a Ferroxidase That Maintains Partial Activity in Sex-Linked Anemia Mice

Blood. 2004 May 15;103(10):3933-9. doi: 10.1182/blood-2003-09-3139. Epub 2004 Jan 29.

Abstract

Hephaestin (Hp) plays an important role in intestinal iron absorption and is predicted to be a ferroxidase based on significant sequence identity to the serum multicopper ferroxidase ceruloplasmin. Here, we demonstrate that Hp has both amine oxidase and ferroxidase activity in cultured cells and primary intestinal enterocytes with the use of both gel and solution assays. The specificity of the activity is shown by immunoblotting, immunoprecipitation, and immunodepletion experiments. Surprisingly, the truncated hephaestin expressed in sex-linked anemia (sla) mice still has measurable, but decreased, oxidase activity. Molecular modeling of the truncated hephaestin suggests retention of a minimum catalytic core required for enzymatic activity. We suggest that hephaestin, by way of its ferroxidase activity, facilitates iron export from intestinal enterocytes, most likely in cooperation with the basolateral iron transporter, Ireg1.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amine Oxidase (Copper-Containing) / metabolism
  • Amino Acid Sequence
  • Anemia / genetics*
  • Animals
  • Catalytic Domain
  • Cells, Cultured
  • Ceruloplasmin / metabolism*
  • Enterocytes / enzymology
  • Enterocytes / metabolism
  • Genetic Diseases, X-Linked
  • Iron / metabolism
  • Male
  • Membrane Proteins / analysis
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Mutant Strains
  • Models, Molecular
  • Sequence Deletion

Substances

  • Heph protein, mouse
  • Membrane Proteins
  • Iron
  • Ceruloplasmin
  • Amine Oxidase (Copper-Containing)