The HIF-1α internal ribosome entry site (IRES) is an RNA element

Cis-regulatory element

A cis-regulatory element or cis-element is a region of DNA or RNA that regulates the expression of genes located on that same molecule of DNA . This term is constructed from the Latin word cis, which means "on the same side as". These cis-regulatory elements are often binding sites for one or...

 present in the 5' UTR

Five prime untranslated region

A messenger ribonucleic acid molecule codes for a protein through translation. The mRNA also contains regions that are not translated: in eukaryotes these include the 5' untranslated region, 3' untranslated region, 5' cap and poly-A tail....

 of the mRNA of HIF-1α

HIF1A

Hypoxia-inducible factor 1, alpha subunit , also known as HIF1A, is a protein that in humans is encoded by the HIF1A gene...

 that allows cap-independent translation. The HIF-1α internal ribosome entry site

Internal ribosome entry site

An internal ribosome entry site, abbreviated IRES, is a nucleotide sequence that allows for translation initiation in the middle of a messenger RNA sequence as part of the greater process of protein synthesis...

 (IRES) allows translation to be maintained under hypoxic cell conditions that inhibit cap-dependent translation [1]. The hypoxia-inducible factor-1α protein (HIF-1α) is a subunit of the HIF-1 transcription factor

Transcription factor

In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...

, which induces transcription of several genes involved in the cellular response to hypoxia.