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      Characterization of the human prolyl 4-hydroxylases that modify the hypoxia-inducible factor.

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          Abstract

          The hypoxia-inducible factors (HIFs) play a central role in oxygen homeostasis. Hydroxylation of one or two critical prolines by specific hydroxylases (P4Hs) targets their HIF-alpha subunits for proteasomal degradation. By studying the three human HIF-P4Hs, we found that the longest and shortest isoenzymes have major transcripts encoding inactive polypeptides, which suggest novel regulation by alternative splicing. Recombinant HIF-P4Hs expressed in insect cells required peptides of more than 8 residues, distinct differences being found between isoenzymes. All the HIF-P4Hs hydroxylated peptides corresponding to Pro564 in HIF-1alpha, whereas a Pro402 peptide had 20-50-fold Km values for two isoenzymes but was not hydroxylated by the shortest isoenzyme at all; this difference was not explained by the two prolines being in a -Pro402-Ala- and -Pro564-Tyr-sequence. All the HIF-P4Hs-hydroxylated peptides corresponding to two of three potential sites in HIF-2alpha and one in HIF-3alpha. The Km values for O2 were slightly above its atmospheric concentration, indicating that the HIF-P4Hs are effective oxygen sensors. Small molecule inhibitors of collagen P4Hs also inhibited the HIF-P4Hs, but with distinctly different Ki values, indicating that it should be possible to develop specific inhibitors for each class of P4Hs and possibly even for the individual HIF-P4Hs.

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          Author and article information

          Journal
          J Biol Chem
          The Journal of biological chemistry
          American Society for Biochemistry & Molecular Biology (ASBMB)
          0021-9258
          0021-9258
          Aug 15 2003
          : 278
          : 33
          Affiliations
          [1 ] Collagen Research Unit, Biocenter Oulu and Department of Medical Biochemistry and Molecular Biology, University of Oulu, FIN-90014 Oulu, Finland.
          Article
          S0021-9258(20)84109-X
          10.1074/jbc.M304982200
          12788921
          0b126a30-bafb-4501-94f4-fc9265a4dc6e
          History

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