Hypoxia-inducible factors (HIFs) are rapidly-responding sensors of reductions in local oxygen tensions, prompting changes in gene transcription. Listed here are the 4-prolyl hydroxylase family, members of which have been identified to hydroxylate proline residues in HIF1α (HIF1A; Q16665) leading to an increased degradation through proteasomal hydrolysis. This action requires molecular oxygen and 2-oxoglutarate, and so reduced oxygen tensions prevents HIF1α hydroxylation, allowing its translocation to the nucleus and dimerisation with HIF1β (also known as ARNT; P27540), thereby allowing interaction with the genome as a transcription factor.
