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Related eIF3 subunits TIF32 and HCR1 interact with an RNA recognition motif in PRT1 required for eIF3 integrity and ribosome binding
Author(s) -
Valášek Leoš,
Phan Lon,
Schoenfeld Lori W.,
Valášková Věra,
Hinnebusch Alan G.
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.4.891
Subject(s) - biology , ribosome , eukaryotic small ribosomal subunit , microbiology and biotechnology , protein subunit , initiation factor , eukaryotic initiation factor , ribosome profiling , eif4a1 , eukaryotic translation , translation (biology) , genetics , rna , messenger rna , gene
eIF3 binds to 40S ribosomal subunits and stimulates recruitment of Met‐tRNA i Met and mRNA to the pre‐initiation complex. Saccharomyces cerevisiae contains an ortholog of human eIF3 subunit p35, HCR1, whose interactions with yeast eIF3 are not well defined. We found that HCR1 has a dual function in translation initiation: it binds to, and stabilizes, the eIF3–eIF5– eIF1–eIF2 multifactor complex and is required for the normal level of 40S ribosomes. The RNA recognition motif (RRM) of eIF3 subunit PRT1 interacted simultaneously with HCR1 and with an internal domain of eIF3 subunit TIF32 that has sequence and functional similarity to HCR1. PRT1, HCR1 and TIF32 were also functionally linked by genetic suppressor analysis. We propose that HCR1 stabilizes or modulates interaction between TIF32 and the PRT1 RRM. Removal of the PRT1 RRM resulted in dissociation of TIF32, NIP1, HCR1 and eIF5 from eIF3 in vivo , and destroyed 40S ribosome binding by the residual PRT1–TIF34–TIF35 subcomplex. Hence, the PRT1 RRM is crucial for the integrity and ribosome‐binding activity of eIF3.