The 66 kDa component of eukaryotic initiation factor 3 interacts with globin mRNA and 18 S rRNA in preinitiation complexes

Westermann, Peter; Sohi, Maninder K.; Arnstein, H. R. V.

doi:10.1016/0014-5793(86)80891-2

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…Finally, the presence of eIF3 in the 40 S preinitiation complex is a prerequisite for the 40 S preinitiation complex to bind mRNA (10 -12) to form the 40 S initiation complex (40 S⅐eIF3⅐mRNA⅐Met-tRNA f ⅐eIF2⅐GTP). Consistent with this function, eIF3 has been reported to bind mRNA as well as initiation factors eIF4F, eIF4A, and eIF4B (13,14) that are known to play important roles in the scanning of mRNA by the 40 S preinitiation complex. The precise mechanism by which eIF3 functions in each of the above steps has yet to be elucidated.…”

Section: Eukaryotic Translation Initiation Factor 3 (Eif3)mentioning

confidence: 77%

Biochemical Characterization of Mammalian Translation Initiation Factor 3 (eIF3)

Chaudhuri

Chakrabarti²,

Maitra

1997

Journal of Biological Chemistry

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Eukaryotic translation initiation factor 3 (eIF3), which plays an essential role in initiation of protein synthesis, was purified from rabbit reticulocyte lysates using an assay that specifically measures its ability to stimulate the binding of Met-tRNA f (as a Met-tRNA f ⅐eIF2⅐ GTP ternary complex) to 40 S ribosomal subunits. Purified eIF3 consisted of six major polypeptides of molecular masses 110, 67, 42, 40, 36, and 35 kDa but lacked the 170-kDa polypeptide reported to be a constituent of other eIF3 preparations. Characterization of purified eIF3 lacking the 170-kDa polypeptide showed that the eIF3-mediated 40 S initiation complex formed in the presence of AUG codon efficiently joined 60 S ribosomal subunits in an eIF5-dependent reaction to form a functional 80 S initiation complex. eIF3, which was originally bound to the 40 S initiation complex, was released from the 40 S subunit during the subunit joining reaction. Additionally, chicken antibodies raised against rabbit reticulocyte eIF3 were used to immunochemically characterize eIF3 subunits and to isolate a 3.1-kilobase pair human cDNA that encodes the p110 subunit of mammalian eIF3. The derived amino acid sequence (calculated M r 95,214) shows that the p110 subunit is the mammalian homologue of Saccharomyces cerevisiae protein Prt1p, a subunit of yeast eIF3.

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Section: Eukaryotic Translation Initiation Factor 3 (Eif3)mentioning

confidence: 77%

Biochemical Characterization of Mammalian Translation Initiation Factor 3 (eIF3)

Chaudhuri

Chakrabarti²,

Maitra

1997

Journal of Biological Chemistry

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“…In contrast, the p66 subunit of mammalian eIF3 which does not contain any obvious RNA-binding motif was shown to bind radioactive β-globin RNA in northwestern analysis (20). It is likely that the binding of eIF3 to mRNA (29,30) may occur via the p42 and the p66 subunits.…”

Section: Discussionmentioning

confidence: 95%

Cloning and characterization of the p42 subunit of mammalian translation initiation factor 3 (eIF3): demonstration that eIF3 interacts with eIF5 in mammalian cells

Bandyopadhyay

Maitra

1999

Nucleic Acids Research

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Eukaryotic translation initiation factor 3 (eIF3) is a large multisubunit protein complex that plays an essential role in the binding of the initiator methionyl-tRNA and mRNA to the 40S ribosomal subunit to form the 40S initiation complex. cDNAs encoding all the subunits of mammalian eIF3 except the p42 subunit have been cloned in several laboratories. Here we report the cloning and characterization of a human cDNA encoding the p42 subunit of mammalian eIF3. The open reading frame of the cDNA, which encodes a protein of 320 amino acids (calculated Mr35 614) has been expressed in Escherichia coli and the recombinant protein has been purified to homogeneity. The purified protein binds RNA in agreement with the presence of a putative RNA binding motif in the deduced amino acid sequence. The protein shows 33% identity and 53% similarity with the Tif35p subunit (YDR 429C) of yeast eIF3. Transfection experiments demonstrated that polyhistidine-tagged p42 protein, transiently expressed in human U20S cells, was incorporated into endogenous eIF3. Furthermore, eIF3 isolated from transfected cell lysates contains bound eIF5 indicating that a specific physical interaction between eIF5 and eIF3 may play an important role in the function of eIF5 during translation initiation in eukaryotic cells.

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“…Characterization of rabbit and human eIF3 indicates that the complex has a molecular mass of ϳ600 kDa and that the subunits are present in one copy per particle (10). At least five subunits of mammalian eIF3, p170, p116 or p110, 2 p66, p47, and p44, bind RNA (11)(12)(13)(14)(15)(16)(17). Of these, p66 and p44 have been shown to bind 18 S ribosomal RNA (13,15,18).…”

mentioning

confidence: 99%

“…At least five subunits of mammalian eIF3, p170, p116 or p110, 2 p66, p47, and p44, bind RNA (11-17). Of these, p66 and p44 have been shown to bind 18 S ribosomal RNA (13,15,18). Mammalian eIF3 also cross-links to 40 S ribosomal subunit proteins (19).…”

mentioning

confidence: 99%

Mutually Cooperative Binding of Eukaryotic Translation Initiation Factor (eIF) 3 and eIF4A to Human eIF4G-1

Korneeva

Lamphear²,

Hennigan

et al. 2000

Journal of Biological Chemistry

104

103

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Eukaryotic translation initiation factor 4G-1 (eIF4G) plays a critical role in the recruitment of mRNA to the 43 S preinitiation complex. The central region of eIF4G binds the ATP-dependent RNA helicase eIF4A, the 40 S binding factor eIF3, and RNA. In the present work, we have further characterized the binding properties of the central region of human eIF4G. Both titration and competition experiments were consistent with a 1:1 stoichiometry for eIF3 binding. Surface plasmon resonance studies showed that three recombinant eIF4G fragments corresponding to amino acids 642-1560, 613-1078, and 975-1078 bound eIF3 with similar kinetics. A dissociation equilibrium constant of ϳ42 nM was derived from an association rate constant of 3.9 ؋ 10 4 M ؊1 s ؊1 and dissociation rate constant of 1.5 ؋ 10 ؊3 s ؊1 . Thus, the eIF3-binding region is included within amino acid residues 975-1078. This region does not overlap with the RNA-binding site, which suggests that eIF3 binds eIF4G directly and not through an RNA bridge, or the central eIF4A-binding site. Surprisingly, the binding of eIF3 and eIF4A to the central region was mutually cooperative; eIF3 binding to eIF4G increased 4-fold in the presence of eIF4A, and conversely, eIF4A binding to the central (but not COOH-terminal) region of eIF4G increased 2.4-fold in the presence of eIF3.The initiation of translation in eukaryotes requires multiple initiation factors that stimulate the binding of mRNA and Met-tRNA i 1 to the 40 S ribosomal subunit to form the 48 S preinitiation complex (1). The binding of Met-tRNA i occurs as a ternary complex with eIF2 and GTP. The binding of mRNA is stimulated by the eIF4 factors (eIF4A, eIF4B, eIF4E, and eIF4G). Joining of the 60 S subunit to form the 80 S initiation complex requires hydrolysis of the GTP bound to eIF2, dissociation of the ternary complex, and release of the eIF2⅐GDP binary complex. eIF5 and eIF5B promote these events by stimulating GTP hydrolysis within the ternary complex bound to the 40 S ribosomal subunit (2). eIF1 and eIF1A act synergistically to mediate assembly of initiation complexes at the initiation codon (3).eIF3 is a multisubunit complex that has been implicated in several aspects of 48 S complex formation. It binds the 40 S ribosomal subunit, stabilizes binding of the eIF2⅐GTP⅐Met-tRNA i ternary complex to the 40 S subunit, stimulates binding of mRNA to the 40 S subunit, and promotes dissociation of 80 S ribosomes into 40 S and 60 S subunits (4 -6). Mammalian eIF3 contains 10 non-identical polypeptides termed p170, p116, p110, p66, p48, p47, p44, p40, p36, and p35 (7,8). Five of these polypeptides have identifiable homologs in Saccharomyces cerevisiae (8, 9). Characterization of rabbit and human eIF3 indicates that the complex has a molecular mass of ϳ600 kDa and that the subunits are present in one copy per particle (10). At least five subunits of mammalian eIF3, p170, p116 or p110, 2 p66, p47, and p44, bind RNA (11-17). Of these, p66 and p44 have been shown to bind 18 S ribosomal RNA (13,15,18). Mammalian eIF3 als...

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The 66 kDa component of eukaryotic initiation factor 3 interacts with globin mRNA and 18 S rRNA in preinitiation complexes

Cited by 10 publications

References 20 publications

Biochemical Characterization of Mammalian Translation Initiation Factor 3 (eIF3)

Biochemical Characterization of Mammalian Translation Initiation Factor 3 (eIF3)

Cloning and characterization of the p42 subunit of mammalian translation initiation factor 3 (eIF3): demonstration that eIF3 interacts with eIF5 in mammalian cells

Mutually Cooperative Binding of Eukaryotic Translation Initiation Factor (eIF) 3 and eIF4A to Human eIF4G-1

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