About: Initiation factor is a research topic. Over the lifetime, 4346 publications have been published within this topic receiving 271241 citations. The topic is also known as: peptide initiation factors & peptide initiation factor.
TL;DR: A ribosomesome-profiling strategy based on the deep sequencing of ribosome-protected mRNA fragments is presented and enables genome-wide investigation of translation with subcodon resolution and is used to monitor translation in budding yeast under both rich and starvation conditions.
Abstract: Techniques for systematically monitoring protein translation have lagged far behind methods for measuring messenger RNA (mRNA) levels. Here, we present a ribosome-profiling strategy that is based on the deep sequencing of ribosome-protected mRNA fragments and enables genome-wide investigation of translation with subcodon resolution. We used this technique to monitor translation in budding yeast under both rich and starvation conditions. These studies defined the protein sequences being translated and found extensive translational control in both determining absolute protein abundance and responding to environmental stress. We also observed distinct phases during translation that involve a large decrease in ribosome density going from early to late peptide elongation as well as widespread regulated initiation at non-adenine-uracil-guanine (AUG) codons. Ribosome profiling is readily adaptable to other organisms, making high-precision investigation of protein translation experimentally accessible.
TL;DR: Protein kinases that phosphorylate the alpha subunit of eukaryotic initiation factor 2 (eIF2alpha) are activated in stressed cells and negatively regulate protein synthesis, resulting in the induction of the downstream gene CHOP (GADD153).
TL;DR: This work has provided a solid foundation for studying the regulation of translation initiation by mechanisms that include the modulation of initiation factor activity and through sequence-specific RNA-binding proteins and microRNAs (which affect individual mRNAs).
Abstract: Protein synthesis is principally regulated at the initiation stage (rather than during elongation or termination), allowing rapid, reversible and spatial control of gene expression. Progress over recent years in determining the structures and activities of initiation factors, and in mapping their interactions in ribosomal initiation complexes, have advanced our understanding of the complex translation initiation process. These developments have provided a solid foundation for studying the regulation of translation initiation by mechanisms that include the modulation of initiation factor activity (which affects almost all scanning-dependent initiation) and through sequence-specific RNA-binding proteins and microRNAs (which affect individual mRNAs).
TL;DR: The recent determination of the structure of eIF4E at atomic resolution has provided insight about how translation is initiated and regulated and suggests that eif4F is also implicated in malignancy and apoptosis.
Abstract: ▪ Abstract Eukaryotic translation initiation factor 4F (eIF4F) is a protein complex that mediates recruitment of ribosomes to mRNA. This event is the rate-limiting step for translation under most circumstances and a primary target for translational control. Functions of the constituent proteins of eIF4F include recognition of the mRNA 5′ cap structure (eIF4E), delivery of an RNA helicase to the 5′ region (eIF4A), bridging of the mRNA and the ribosome (eIF4G), and circularization of the mRNA via interaction with poly(A)-binding protein (eIF4G). eIF4 activity is regulated by transcription, phosphorylation, inhibitory proteins, and proteolytic cleavage. Extracellular stimuli evoke changes in phosphorylation that influence eIF4F activity, especially through the phosphoinositide 3-kinase (PI3K) and Ras signaling pathways. Viral infection and cellular stresses also affect eIF4F function. The recent determination of the structure of eIF4E at atomic resolution has provided insight about how translation is initiat...
TL;DR: A novel mechanism of initiation on poliovirus RNA occurs by binding of ribosomes to an internal sequence within the 5′ noncoding region, which may explain the disparate translation of several other eukaryotic messenger RNAs.
Abstract: Poliovirus RNA is naturally uncapped, therefore its translation must proceed via a cap-independent mechanism. Translation initiation on poliovirus RNA occurs by binding of ribosomes to an internal sequence within the 5' noncoding region. This novel mechanism of initiation may explain the disparate translation of several other eukaryotic messenger RNAs.