Hypoxia-inducible factor-proline dioxygenase contains iron, and requires ascorbate.
Hypoxia-inducible factor (HIF) is an evolutionarily conserved transcription factor[7] that allows the cell to respond physiologically to low concentrations of oxygen.[8] A class of prolyl hydroxylases which act specifically on HIF has been identified;[9] hydroxylation of HIF allows the protein to be targeted for degradation.[9] HIF prolyl-hydroxylase has been targeted by a variety of inhibitors that aim to treat stroke,[10] kidney disease,[11]ischemia,[12]anemia,[13] and other important diseases. Clinically observed prolyl hydroxylase domain mutations, as in the case of erythrocytosis- and breast cancer-associated PHD2 mutations, affect its selectivity for its HIF substrate, which has important implication for drug design.[14]
In humans, there are three isoforms of hypoxia-inducible factor-proline dioxygenase. These are PHD1, PHD2 and PHD3. PHD2, in particular, was identified as the most important human oxygen sensors due to its slow reaction with oxygen.[15]
^Oehme, F.; Ellinghaus, P.; Kolkhof, P.; Smith, T.J.; Ramakrishnan, S.; Hutter, J.; Schramm, M.; Flamme, I. (2002). "Overexpression of PH-4, a novel putative proline 4-hydroxylase, modulates activity of hypoxia-inducible transcription factors". Biochem. Biophys. Res. Commun. 296 (2): 343–349. doi:10.1016/S0006-291X(02)00862-8. PMID12163023.
^McNeill, L.A.; Hewitson, K.S.; Gleadle, J.M.; Horsfall, L.E.; Oldham, N.J.; Maxwell, P.H.; Pugh, C.W.; Ratcliffe, P.J.; Schofield, C.J. (2002). "The use of dioxygen by HIF prolyl hydroxylase (PHD1)". Bioorg. Med. Chem. Lett. 12 (12): 1547–1550. doi:10.1016/S0960-894X(02)00219-6. PMID12039559.
^Bacon, N. C.; Wappner, P; O'Rourke, J. F.; Bartlett, S. M.; Shilo, B; Pugh, C. W.; Ratcliffe, P. J. (1998). "Regulation of the Drosophila bHLH-PAS protein Sima by hypoxia: Functional evidence for homology with mammalian HIF-1 alpha". Biochemical and Biophysical Research Communications. 249 (3): 811–6. doi:10.1006/bbrc.1998.9234. PMID9731218.