Gene expression translational control

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). 

Suess B, Hanson S, Berens C, Fink B, Schroeder R, Hillen W, Conditional gene expression by controlling translation with tetracycline-binding aptamers, Nucleic Acids Res., 31 1853-1858, 2003. 

Clearly, the control of gene expression at the transcriptional level is a key regulatory mechanism controlling carotenogenesis in vivo. However, post-transcriptional regulation of carotenoid biosynthesis enzymes has been found in chromoplasts of the daffodil. The enzymes phytoene synthase (PSY) and phytoene desaturase (PDS) are inactive in the soluble fraction of the plastid, but are active when membrane-bound (Al-Babili et al, 1996 Schledz et al, 1996). The presence of inactive proteins indicates that a post-translational regulation mechanism is present and is linked to the redox state of the membrane-bound electron acceptors. In addition, substrate specificity of the P- and e-lycopene cyclases may control the proportions of the p, P and P, e carotenoids in plants (Cunningham et al, 1996). 

In 1976, Hamish Munro proposed a model for the translational control of ferritin synthesis (Zahringer et al., 1976), which not only represents a crucial and remarkably far-sighted contribution to our understanding of cellular iron metabolism, but also in the more general context of the posttranscriptional control of gene expression. 

Donahue, T. (2000). Genetic approaches to translation initiation in Saccharomyces cerevisiae. In Translational Control of Gene Expression (N. Sonenberg, J. W. B. Hershey, and M. B. Mathews, eds.), pp. 487—502. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York. 

Regulation of neuropeptide expression is exerted at several levels. Control of neuropeptide function is mediated by factors controlling rates of prepropeptide gene transcription, translation, peptide degradation and secretion (Fig. 18-11). On the scale of seconds to minutes, peptide secretion is not always coupled lock-step with classical transmitter release (example above). Peptides are inactivated by diffusion and by proteolysis, so it would be expected that inhibition of specific extracellular proteases... 

Most genes contain the information needed to make functional molecules called proteins. (A few genes produce other molecules that help the cell assemble proteins.) The journey from gene to protein is complex and tightly controlled within each cell. It consists of two major steps transcription and translation. Together, transcription and translation are known as gene expression. 

Caskey CT, Forrester WC, Tate W (1984) Peptide chain termination. In Clark BFC, Petersen HU (eds) Gene expression the translational step and its control. Munksgaard, Copenhagen... 

HATs catalyze the post-translational acetylation of amino-terminal lysine tails of core histones, which results in disruption of the repressive chromatin folding and an increased DNA accessibility to regulatory proteins. The level of histone acetylation is highly controlled and balanced by the activity of histone deacetylases (HDACs), the opponents of HATs. Generally, acetylation is correlated with activation and deacetylation with repression of gene expression. Therefore, the dynamic equilibrium of these proteins represents a key mechanism of gene regulation. 

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