Preferred Label : Internal Ribosome Entry Pathway;
Alternative definition : BIOCARTA: Control of translation is one of the major regulatory events in eukaryotic
gene expression. Internal ribosome entry sites (IRES) were first discovered in picornavirus
RNAs but it is now clear that IRESs are also present in the 5' untranslated region
of many eukaryotic genes including those encoding growth factors (e.g., VEGF, FGF2
and PDGF), genes whose protein products are associated with apoptosis (e.g., Apaf-1,
IXAP), transcription factors (e.g., c- myc), and the potassium channel Kv1.4. IRES
allows the ribosomes to be recruited to an initiator AUG, which is some distance from
the 5' end of the message RNA to bypass the Kozak scanning mechanism. In the Kozak
scanning model, the 40S ribosomal subunit bearing Met-tRNAmet and initiation factors,
binds near the capped 5' end of the mRNA and travels along the mRNA until it comes
to the first AUG. IRES-dependent initiation of protein synthesis occurs during apoptosis
or some viral infection (e.g., picornavirus). A component of the cap-binding complex
eIF-4F, translation initiation factor eIF-4G, is cleaved (by caspases or viral protein
2A) to give a modified form of cap-binding complex that is cap-independent. (This
definition may be outdated - see the DesignNote.);
NCIt note : The BIOCARTA Definition (ALT_DEFINITION) for this pathway concept was provided by
BioCarta. This property was not created by, nor is it maintained by the NCI Thesaurus
staff. Additionally, BioCarta is no longer updating its pathway data; thus, the BIOCARTA
Definition might be outdated or inaccurate. Please see the Terms and Conditions for
Use at http://www.biocarta.com/.;
Biocarta ID : h_iresPathway;
Origin ID : C39134;
UMLS CUI : C1512885;
Semantic type(s)
- has_gene_product_element
- pathway_has_gene_element
