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. Author manuscript; available in PMC: 2012 Jul 1.
Published in final edited form as: Biochim Biophys Acta. 2010 Aug 21;1813(7):1263–1268. doi: 10.1016/j.bbamcr.2010.08.006

Fig. 2.

Fig. 2

Negative regulation of HIF-1 activity by oxygen. Top: In the presence of O2: prolyl hydroxylation of HIF-1a leads to binding of the von Hippel-Lindau protein (VHL), which recruits a ubiquitin protein-ligase that targets HIF-1a for proteasomal degradation; and asparaginyl hydroxylation of HIF-1a blocks the binding of the coactivator protein p300. Bottom: Under hypoxic conditions, the hydroxylation reactions are inhibited, leading to decreased VHL binding and protein stabilization as well as increased p300 binding and transcriptional activation.