Translation initiation and

As mentioned above, mammahan mRNA molecules contain a 7-methylguanosine cap structure at their 5 terminal, and most have a poly(A) tail at the 3 terminal. The cap stmcmre is added to the 5 end of the newly transcribed mRNA precursor in the nucleus prior to transport of the mELNA molecule to the cytoplasm. The S cap of the RNA transcript is required both for efficient translation initiation and protection of the S end of mRNA from attack by S —> S exonucleases. The secondary methylations of mRNA molecules, those on the 2 -hydroxy and the N of adenylyl residues, occur after the mRNA molecule has appeared in the cytoplasm. 

This chapter presents methods and protocols suitable for the identification and characterization of inhibitors of the prokaryotic and/or eukaryotic translational apparatus as a whole or targeting specific, underexploited targets of the bacterial protein synthetic machinery such as translation initiation and amino-acylation. Some of the methods described have been used successfully for the high-throughput screening of libraries of natural or synthetic compounds and make use of model universal mRNAs that can be translated with similar efficiency by cellfree extracts of bacterial, yeast, and HeLa cells. Other methods presented here are suitable for secondary screening tests aimed at identifying a ... 

The application of forward chemical genetics to studies of translation provides an opportunity to identify small molecules that inhibit or stimulate this process without any underlying assumptions as to which step is most amenable to targeting by the chemical libraries under consideration. The opportunity exists to identify novel factors involved in translation, unravel new activities of known translation initiation factors, or characterize shortlived intermediates that are frozen by the small molecule inhibitor. We have undertaken a forward chemical genetic approach to identify small molecules that inhibit or stimulate translation in extracts prepared from Krebs-2 ascites cells (Novae et al., 2004). These screens have led to the identification of several novel inhibitors of translation initiation and elongation (Bordeleau et al., 2005, 2006 Robert et al., 2006a,b). 

Sachs AB, Davis RW (1990) Translation initiation and ribosomal biogenesis involvement of a putative rRNA helicase and RPL46. Science 247 1077—1079... 

The 5 and 3 UTRs of eukaryotic mRNA are crucial for the regulation of gene expression by controlling mRNA translational efficiency, stability, and localization. The 5 cap and poly A (pA), found on almost all eukaryotic mRNAs, stimulate translation initiation and stabilize mRNA in synergy. However, for in vitro translation, the use of 5 cap and pA can be a major problem, as described Chapter 11 by Endo and Sawasaki. These problems have been effectively overcome by optimizing the 5 and 3 UTRs (12). 

Structurally, the SSU rRNA can be divided into three major domains and a 3 minor domain [61,77]. The 3 minor domain is involved in translational initiation and decoding, the 3 major domain in elongation and termination, the central domain in subunit association and the 5 domain in translational accuracy [72,73,77]. 

Multiple inhibitors In vitro translation extract Inhibition of translation initiation and elongation RNA and varied... 

INTERNET LINK Translation Initiation and Elongation Factors... 

Despite the importance of alternative splicing for the diversity of the proteome and regulation of gene expression two aspects of protein-coding mRNAs— alternative translation initiation and short peptides—have not yet been touched upon. Alternative translation initiation can generate from one transcript two or more protein isoforms. In the case of leaky scanning the ribosome bypasses the... 

Originally two alternative models were proposed for the internal initiator, P2 [134,135]. One model pictured P2 as a special translation initiator, and the other considered P2 as a transcription initiator or promoter. Morse and Yanofsky [137] concluded that in E. coli it was... 

T. Von der Haar, J.M.X. Hughes, M.M. Karim, M. Ptushkina, and J.E.G. McCarthy, Translation initiation and surface plasmon resonance new technology applied to old questions. Biochemical Society Transactions 30 (2002) 155-162. 

Column 3 RNA species. RNAs and pol mucleotides arranged alphabetically under each metal oxidation state and metal complex first by polyribonucleotide species, then by tRNA species in order of amino acid and then source organism, mixed (unfractionated) species listed after those identified by amino acid, and finally by RNA species other than tRNAs. Amino acids are abbreviated by the three letter nomenclature, Ala , Arg , etc. Met P and Met m .represent the translational initiator and the ordinary methionine spedes, respectively. TYMV=turnip yellow mosaic virus. TMV=tobacco mosaic virus. 

Nonstandard Modes of Translation Initiation and Translational Controls of Gene Expression... 

These results demonstrate that short-term EAA starvation of mammary epithelial cells alters the phosphorylation state of eIF2a, and the effects can be reversed by the addition of at least Phe, His, or Val. This was an exploratory experiment. More research is needed to determine the long-term effects of individual EAA on the regulation of translation initiation and protein synthesis in mammary epithelial cells. 

Landau G, Bercovich Z, Park MH, Kahana C (2010) The role of polyamines in supporting growth of mammalian cells is mediated through their requirement for translation initiation and elongation. J Biol Chem 285 12474-12481... 

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