Functional diversity of the eukaryotic translation initiation factors belonging to eIF4 families

Hernández, Greco; Vázquez-Pianzola, Paula

doi:10.1016/j.mod.2005.04.002

Cited by 129 publications

(115 citation statements)

References 116 publications

(212 reference statements)

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“…4 The exact role(s) of the RNA helicase, eIF4A, in initiation is incompletely defined but putative tasks for this peptide include dissociation of higher order RNA structure to enhance cap binding, and in scanning of 43S complex components from the cap to the start codon. 7,8 As might be expected, the activity of the cap-binding complex is controlled and can be modulated by regulatory proteins to augment or diminish translational gene expression. 1 We serendipitously discovered that bunyavirus N serves as a translation initiation factor when the expression of various reporter genes was curiously amplified in the presence of N. 9 Systematic analysis of the phenomenon indicated that N augments the translational expression of mRNA by either mimicking or obviating the requirement for the activities of the cap-binding complex.…”

Section: Bunyavirus N Protein Is a Translation Initiation Factormentioning

confidence: 90%

Bunyavirus N: eIF4F surrogate and cap-guardian

Panganiban¹,

Mir²

2009

Cell Cycle

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Section: Bunyavirus N Protein Is a Translation Initiation Factormentioning

confidence: 90%

Bunyavirus N: eIF4F surrogate and cap-guardian

Panganiban¹,

Mir²

2009

Cell Cycle

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“…Hernández and Vazquez-Pianzola (29) have suggested that there is one eIF4E family member in each organism that is ubiquitously and constitutively expressed to carry out general translation and that others are involved in specialized functions, both translational and non-translational. Examples of this are beginning to emerge (Table 1).…”

Section: Physiological Roles For Specific Eif4e Family Membersmentioning

confidence: 99%

eIF4E: New Family Members, New Binding Partners, New Roles

Rhoads

2009

Journal of Biological Chemistry

145

169

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Eukaryotic initiation factor 4E (eIF4E) has long been known as the cap-binding protein that participates in recruitment of mRNA to the ribosome. A number of recent advances have not only increased our understanding of how eIF4E acts in translation but also uncovered non-translational roles. New structures have been determined for eIF4E in complex with various ligands and for other cap-binding proteins. We have also learned that most eukaryotic organisms express multiple eIF4E family members, some involved in general translation but others having specialized functions, including repression of translation. A number of new eIF4E-binding proteins have been reported, some of which tether it to specific mRNAs.The 7-methylguanosine-containing "cap" plays an essential role at each stage of the mRNA "life cycle": transcription, splicing, nuclear export, translation, translational repression, and degradation. This is mediated by specific cap-binding proteins, of which at least 10 have been discovered so far (supplemental Table S1). The most widely studied and best understood of these cap-binding proteins is eIF4E.2 eIF4E was discovered as a protein that promotes translation initiation, and most of the work on its structure, function, and regulation has been performed with this role in mind. As a canonical initiation factor involved in recruitment of mRNA to the ribosome, eIF4E has the potential to influence expression of virtually every protein in the cell. It is against this backdrop of eIF4E serving as a translational enhancer that discoveries over the past decade have been so surprising, that eIF4E can also function as a translational repressor. Another unexpected result of recent research is that nearly all eukaryotes express multiple eIF4E family members and that they can have different functions in the cell. A third research trend has been the discovery of new eIF4E-binding partners, some of which tether eIF4E to specific mRNAs. This minireview touches on all of these new directions in eIF4E research. Role of eIF4E in TranslationRecruitment of mRNA to the 43 S initiation complex to form the 48 S initiation complex requires eIF3, the poly(A)-binding protein, and the eIF4 proteins (Fig. 1B) (1). The eIF4 factors consist of eIF4A, a 46-kDa RNA helicase; eIF4B, a 70-kDa RNA-binding and RNA-annealing protein; eIF4E, a 25-kDa cap-binding protein; eIF4H, a 25-kDa protein that acts with eIF4B to stimulate eIF4A helicase activity; and eIF4G, a 185-kDa protein that co-localizes all of the other proteins involved in mRNA recruitment on the 40 S subunit.3 At least four cis-acting elements affect the efficiency of mRNA translation: the cap, the poly(A) tail, sequence elements in the 5Ј-UTR, and sequence elements in the 3Ј-UTR. It is well established that eIF4E stimulates translation of capped mRNAs, but mRNAs differ in their dependence on eIF4E. For instance, mRNAs with extensive 5Ј-UTR secondary structure have a greater requirement for the eIF4A-based unwinding machinery recruited by eIF4E (Fig. 1B) (2).The tertiary structures ...

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“…Mammalian eIF4F complexes contain eIF4A, the prototype of the DEAD box helicase family (7,8); however, plant eIF4A is loosely associated and is easily removed during purification (9). eIF4G is a multifunctional protein that is an important structural platform for the assembly or nucleation of several initiation factors (eIF4A, eIF3, eIF4B, eIF5, and poly(A)-binding protein) and interaction with the 40 S ribosome during the initiation process (10,11). Furthermore, in mammals there is also interaction of eIF4G with MNK kinase that then phosphorylates associated eIF4E (12).…”

mentioning

confidence: 99%

Plant Cap-binding Complexes Eukaryotic Initiation Factors eIF4F and eIFISO4F

Mayberry

Allen

Nitka

et al. 2011

Journal of Biological Chemistry

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Background: Plants have a unique form of cap-binding complex. Results: Correct and mixed complexes show differential translation, and mixed complex subunits have lower binding affinity than correct complex subunits. Conclusion:The subunits of the cap-binding complexes show specificity for complex formation, and the translational efficiency is determined by the large subunit. Significance: The results suggest the potential for differential translation by the two plant cap-binding complexes.

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Functional diversity of the eukaryotic translation initiation factors belonging to eIF4 families

Cited by 129 publications

References 116 publications

Bunyavirus N: eIF4F surrogate and cap-guardian

Bunyavirus N: eIF4F surrogate and cap-guardian

eIF4E: New Family Members, New Binding Partners, New Roles

Plant Cap-binding Complexes Eukaryotic Initiation Factors eIF4F and eIFISO4F

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