Regulation at translation level

Content
Regulation of Gene Expression 3. A Variety of Mechanisms in Eukaryotes
Regulation at Transcription Level
Activation of transcription
Britten-Davidson model for unit of transcription
Gene battery
Chromosomal proteins and gene expression
Repression of transcription 
Specific DNA sequences controlling transcription
Transgenic plants to study regulatory sequences
Modification of DNA sequences and their transcripts in gene expression
Alternative splicing of transcripts
Regulation at translation level
Activation and repression of translation
Masked mRNA in eggs of sea urchin and Xenopus
Regulation by gene re-arrangement
Expression of immunoglobulin genes
Yeast mating type switching
Trypanosome surface antigen (VSG) switching
Synthesis of mRNA in pieces in VSG genes in trypanosome
Regulation by reversible phosphorylation
Signal transduction and second messengers
Proteins and peptide hormones and gene expression
Steroid hormones and gene expression
Interferon stimulated gene expression (without a second messenger)
Cell surface receptors in cholesterol metabolism and drug production
Ubiquitin protein and regulation of heat shock genes
Regulation at Translation Level
Information about translational control in eukaryotes is coming from experiments designed to answer following questions regarding the mechanism of operation of translational machinery.

(i) When there are more than one AUG codons in a mRNA molecule, how does the ribosome know, which one to use for initiation of translation ? (ii) What determines the frequency with which a particular mRNA message is read ? (iii) After finishing translation of an open reading frame (ORF), can a ribosome start again, if an AUG codon follows in the same mRNA within a reasonable length ? (iv) Can a mRNA remain untranslated in a cell and translated only when necessary ?

It has been possible to determine the nucleotide sequence of natural mRNA, to alter these mRNAs as desired and to make synthetic mRNA using recombinant DNA methods. These techniques helped in answering some of the above questions and also yielded information regarding regulation of gene expression at the level of translation. This has partly been discussed in Expression of Gene : Protein Synthesis 4. Translation in Prokaryotes and Eukaryotes, while describing Kozak's scanning hypothesis for reading of mRNA by ribosomes in eukaryotes.