This observation suggested that in Y cells, while p16 mRNA associated extensively with the translational machinery, it was not actively translated, possibly through an inhibition of translational elongation.
Ire1p splices HAC1 mRNA and only then Hac1p is actively translated and capable of activating its downstream genes [ 1].
The translational coupling system was used to determine that a large multi-domain enzyme was not actively translated in E. coli, to isolate the translation problems to the C-terminal domains, and to optimize conditions for expressing a codon-optimized sequence variant.
Most studies determine mRNAs translation levels as log ratios of actively translated mRNAs divided by the corresponding cytosolic mRNA levels, obtained in parallel.
It has been shown that calculating mRNA translation levels as log ratios of actively translated mRNAs divided by the corresponding cytoplasmic mRNA results in a significant number of false positives and false negatives (Larsson et al., 2010).
Therefore, it is evident that the transcriptome does not necessarily represent the current state of the proteome, but is rather a mixture of transcripts being actively translated and others that are standing by, awaiting activation by post-transcriptional regulatory mechanisms.
The long 3′UTR represses translation at rest, while the short transcript is actively translated.
Using microarray analysis of actively translated polysomal mRNA, we found that EtOH affected the translation of fewer mRNAs than INK128.
These different fates of transcripts have been associated with specific subcellular localizations: mRNAs being actively translated are associated with polysomes; mRNAs targeted for degradation or translation repression accumulate in P-bodies (a.k.a. mRNA processing bodies or GW bodies); and, in response to stress conditions, mRNAs stalled in translation initiation accumulate in stress granules.
In the cytoplasm, mRNAs actively translated by polyribosomes are targeted by miRISC complexes to suppress translation [ 54].
