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. Author manuscript; available in PMC: 2011 Nov 14.
Published in final edited form as: Curr Opin Genet Dev. 2007 Jan 8;17(1):71–77. doi: 10.1016/j.gde.2006.12.006

Figure 2.

Figure 2

Regulation of HIF-α stability: continuously transcribed and translated, the HIF-α subunits are degraded under normoxic conditions. Two prolines in the ODD are hydroxylated by PHD1, 2 or 3, allowing recognition by an E3 ubiquitin ligase complex including the VHL tumor suppressor protein. Following pVHL-mediated ubiquitylation, the HIF-α subunits are degraded in a proteasome-dependent fashion. When oxygen levels fall below ~5%, the PHDs are no longer active and the HIF-α subunits can translocate to the nucleus, where they bind co-factors including ARNT and p300 and transactivate hypoxia response genes, such as VEGF and PGK.