Abstract
Components of the translation apparatus, including ribosomal proteins, have been found in cell nuclei in various organisms. Components of the translation apparatus are involved in various nuclear processes, particularly those associated with genome integrity control and the nuclear stages of gene expression, such as transcription, mRNA processing, and mRNA export. Components of the translation apparatus control intranuclear trafficking; the nuclear import and export of RNA and proteins; and regulate the activity, stability, and functional recruitment of nuclear proteins. The nuclear translocation of these components is often involved in the cell response to stimulation and stress, in addition to playing critical roles in oncogenesis and viral infection. Many components of the translation apparatus are moonlighting proteins, involved in integral cell stress response and coupling of gene expression subprocesses. Thus, this phenomenon represents a significant interest for both basic and applied molecular biology. Here, we provide an overview of the current data regarding the molecular functions of translation factors and ribosomal proteins in the cell nucleus.
Highlights
MRNA translation is performed by a large number of highly conserved proteins and RNAs
Translation initiation factors are highly conserved and include the eukaryotic initiation factors eIF1, eIF1A, eIF1B, eIF2, eIF2A, eIF2B, eIF3, eIF4A, eIF4B, eIF4E, eIF4G, eIF4H, eIF5, eIF5B, and auxiliary eIF6
A significant pool of the translation initiation factor eIF4G is localized in the nuclei of mammalian cells, where it interacts with the cap-binding complex (CBC) but not with nuclear eIF4E. eIF4G interacts with spliceosomal snRNPs and splicing factors. eIF4G is recruited to pre-mRNA via the CBC, and this complex is exported to the cytoplasm [342]
Summary
MRNA translation is performed by a large number of highly conserved proteins and RNAs. The main components of the translation apparatus (CTAs) include translation factors, ribosomal proteins (RPs), and ribosomal RNAs (rRNAs) [1]. The eukaryotic 80S ribosome consists of two subunits, the 40S and the 60S. The core group of proteins that govern translation includes initiation, elongation, and termination/release factors. Translation initiation factors are highly conserved and include the eukaryotic initiation factors (eIFs) eIF1, eIF1A, eIF1B, eIF2 (a complex consisting of three subunits; eIF2S1 is known as eIF2α), eIF2A, eIF2B (a complex consisting of five subunits), eIF3 (a complex consisting of up to 13 subunits), eIF4A, eIF4B, eIF4E, eIF4G, eIF4H, eIF5, eIF5B, and auxiliary eIF6. The eukaryotic elongation factors (eEFs) include eEF1A, eEF1B (a complex consisting of two to four subunits), eEF2, eIF5A, and eEFSec. The eukaryotic release factors include eRF1 and eRF3. The functioning of the core apparatus is accompanied by other proteins, in addition to these factors [1,10,11,12,13,14,15,16]
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