Eukaryotic translation initiation factor 1 (eIF1) is a protein that in humans is encoded by the EIF1gene. It is related to yeast SUI1.[5][6][7]
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]
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]
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]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Fields C, Adams MD (January 1994). "Expressed sequence tags identify a human isolog of the suil translation initiation factor". Biochemical and Biophysical Research Communications. 198 (1): 288–291. Bibcode:1994BBRC..198..288F. doi:10.1006/bbrc.1994.1040. PMID7904817.
^Hinnebusch AG (August 2017). "Structural Insights into the Mechanism of Scanning and Start Codon Recognition in Eukaryotic Translation Initiation". Trends in Biochemical Sciences. 42 (8): 589–611. doi:10.1016/j.tibs.2017.03.004. PMID28442192.
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Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek EJ, et al. (January 2005). "Immunoaffinity profiling of tyrosine phosphorylation in cancer cells". Nature Biotechnology. 23 (1): 94–101. doi:10.1038/nbt1046. PMID15592455. S2CID7200157.
