title: Cloning of a novel prolyl 4-hydroxylase subunit expressed in the fibrous cap of human atherosclerotic plaque.
abstract: BACKGROUND
  The production of collagen is fundamental to atherosclerosis and critically dependent on posttranslational modification by prolyl 4-hydroxylase.
  
  
  RESULTS
  We report the cloning of a novel prolyl 4-hydroxylase catalytic (alpha) subunit from human vascular smooth muscle cells. The peptide displayed conservation of critical residues for interacting with Fe2+ and 2-oxoglutarate, essential cosubstrates for prolyl 4-hydroxylase activity. Furthermore, when the recombinant protein was expressed in cells, it associated with the beta-subunit of prolyl 4-hydroxylase and could catalyze prolyl 4-hydroxylation of a collagen-like peptide. The tissue distribution was dissimilar from that of the 2 previously cloned alpha-subunits, suggesting a role beyond redundancy. Importantly, the novel gene was expressed in the fibrous cap of human carotid atherosclerotic lesions.
  
  
  CONCLUSIONS
  The discovery of a novel prolyl 4-hydroxylase alpha-subunit, here termed the alpha(III)-subunit, suggests a new participant in collagen synthesis that, in view of the expression findings, may be relevant to atherosclerotic disease.
authors.affiliation: Robarts Research Institute (Vascular Biology Group), London Health Sciences Centre, Department of Medicine (Cardiology), University of Western Ontario, London, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Van Den Diepstraten
authors.forename: Karen
authors.initials: K
authors.lastname: Papay
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Bolender
authors.forename: Arthur
authors.initials: A
authors.lastname: Brown
authors.forename: J Geoffrey
authors.initials: JG
authors.lastname: Pickering
mesh_terms: D001161:Arteriosclerosis / Q000150:complications / Q000201:enzymology* / Q000473:pathology; D015152:Blotting, Northern; D002340:Carotid Artery Diseases / Q000201:enzymology / Q000473:pathology; D020134:Catalytic Domain / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D003094:Collagen / Q000378:metabolism; D004789:Enzyme Activation; D005355:Fibrosis / Q000150:complications / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D009928:Organ Specificity; D011393:Procollagen-Proline Dioxygenase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D021122:Protein Subunits / Q000096:biosynthesis / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D021122:Protein Subunits; D003094:Collagen; C477143:P4HA3 protein, human; D011393:Procollagen-Proline Dioxygenase