EIF1

Eukaryotic translation initiation factor 1 (eIF1) is a protein that in humans is encoded by the EIF1 gene. It is related to yeast SUI1.^[5][6][7]

EIF1
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2IF1, 4KZX, 4KZY
Identifiers
Aliases	EIF1, A121, EIF-1, ISO1, SUI1, eukaryotic translation initiation factor 1, Eukaryotic initiation factor 1
External IDs	MGI: 105125; HomoloGene: 130538; GeneCards: EIF1; OMA:EIF1 - orthologs
Gene location (Human) Chr. Chromosome 17 (human)[1] Band 17q21.2 Start 41,688,885 bp[1] End 41,692,668 bp[1]
Gene location (Mouse) Chr. Chromosome 11 (mouse)[2] Band 11|11 D Start 100,210,711 bp[2] End 100,212,922 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in sperm oocyte parotid gland parietal pleura tail of epididymis lower lobe of lung secondary oocyte vena cava caput epididymis visceral pleura Top expressed in granulocyte muscle of thigh morula blastocyst superior frontal gyrus right kidney ventricular zone neural tube extensor digitorum longus muscle embryo More reference expression data BioGPS n/a
Gene ontology Molecular function translation factor activity, RNA binding translation initiation factor activity RNA binding protein binding ribosomal small subunit binding Cellular component cytoplasm nucleus eukaryotic 43S preinitiation complex Biological process translational initiation response to stress dosage compensation by inactivation of X chromosome protein biosynthesis regulation of translational initiation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 10209 20918 Ensembl ENSG00000173812 ENSMUSG00000035530 UniProt P41567 P48024 RefSeq (mRNA) NM_005801 NM_011508 RefSeq (protein) NP_005792 NP_035638 Location (UCSC) Chr 17: 41.69 – 41.69 Mb Chr 11: 100.21 – 100.21 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

eIF1 interacts with the eukaryotic small (40S) ribosomal subunit and eIF3, and is a component of the 43S preinitiation complex (PIC).^[8] eIF1 and eIF1A bind cooperatively to the 40S to stabilize an "open" conformation of the preinitiation complex (PIC) during eukaryotic translation initiation.^[8] eIF1 binds to a region near the ribosomal P-site in the 40S subunit and functions in a manner similar to the structurally related bacterial counterpart IF3.^[9]

Structure

eIF1's structure was first determined in 1999 by solution-state NMR spectroscopy, which revealed that it consists of a five-stranded beta-sheet which is sided by two alpha-helices.^[10] Crystallographic experiments showed that eIF1 is located at the P-site of the small ribosomal subunit, binding to the 18S rRNA with a basic surface.^[11] To date, a number of cryo-EM structures have been solved that include eIF1 in the context of various translation initiation complexes.^[12][13][14]

Function

In eukaryotic cells, translation initiation on an mRNA involves scanning of the mRNA by the 43S pre-initiation complex in search of the translation initiation start codon.^[15] Accurate identification of the start codon is very important, as other translation start sites may lead to the production of defect proteins. A codon is detected as a start codon by interaction with the tRNA's anticodon that is positioned in the P-site of the small ribosomal subunit, which leads to closing of the pre-initiation complex.^[16] eIF1 is positioned on the small ribosomal subunit such that it blocks the closure of the pre-initiation complex. It thereby aids in selecting the correct start codon, since only the correct codon-anticodon interaction provides enough energy to displace eIF1 and thus close the pre-initiation complex.^[17]

See also

• Eukaryotic initiation factors^[18]