Abstract
HJV (haemojuvelin) plays a key role in iron metabolism in mammals by regulating expression of the liver-derived hormone hepcidin, which controls systemic iron uptake and release. Mutations in HJV cause juvenile haemochromatosis, a rapidly progressing iron overload disorder in humans. HJV, also known as RGMc (repulsive guidance molecule c), is a member of the three-protein RGM family. RGMs are GPI (glycosylphosphatidylinositol)-linked glycoproteins that share ~50% amino acid identity and several structural motifs, including the presence of 14 cysteine residues in analogous locations. Unlike RGMa and RGMb, HJV/RGMc is composed of both single-chain and two-chain isoforms. To date there is no structural information for any member of the RGM family. In the present study we have mapped the disulfide bonds in mouse HJV/RGMc using a proteomics strategy combining sequential MS steps composed of ETD (electron transfer dissociation) and CID (collision-induced dissociation), in which ETD induces cleavage of disulfide linkages, and CID establishes disulfide bond assignments between liberated peptides. The results of the present study identified an HJV/RGMc molecular species containing four disulfide linkages. We predict using ab initio modelling that this molecule is a single-chain HJV/RGMc isoform. Our observations outline a general approach using tandemMS and ab initio molecular modelling to define unknown structural features in proteins.
Original language | English (US) |
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Pages (from-to) | 87-95 |
Number of pages | 9 |
Journal | Biochemical Journal |
Volume | 452 |
Issue number | 1 |
DOIs | |
State | Published - May 15 2013 |
Keywords
- Disulfide bond
- Haemojuvelin
- Iron metabolism
- Mass spectrometry
- Molecular modelling
- Protein structure
- Repulsive guidance molecule
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology