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. 2019 Nov 1;43(1):3–15. doi: 10.3892/or.2019.7397

Figure 1.

Figure 1.

Structure of HIFs and functional domains. HIF-1α and HIF-2α are highly similar in amino acid sequence, and both contain bHLH, PAS and TAD functional domains (C-TAD and N-TAD), among which C-TAD is enriched with various auxiliary transcription factors such as p300/CBP; HIF-3α contains only bHLH, PAS and N-TAD. Furthermore, the HIF-1α, HIF-2α and HIF-3α structures include the ODDD domain, which acts as a recognition site for the tumor suppressor protein pVHL and is involved in protein stabilization and regulation of intracellular oxygen concentration. HIF-β contains bHLH and PAS, and the HIF-β subunit is not regulated by intracellular oxygen concentration and has no transcriptional activity alone; only heterodimers of HIF-α and -β subunits are active. bHLH, basic helix-loop-helix; C, carboxy-terminus; CBP, CREB-binding protein; HIF, hypoxia-inducible factor; N, amino-terminus; ODDD, oxygen-dependent degradation domain; PAS, Per-ARNT-Sim; pVHL, von Hippel-Lindau tumor suppressor; TAD, transactivation domain; p300/CBP, auxiliary transcription factor.