gene regulation occurs at each step of protein synthesis in eukaryotes. provide one example of gene regulation for each of the following steps of eukaryotic protein synthesis: transcriptional, post-transcriptional, translational, post-translational

Gene regulation

Explanation:

Transcriptional gene regulation:

Eukaryotic gene expression is mainly regulated at transcription level In eukaryotic transcription initiation of a gene require change in chromatin structure (chromatin remodelling) because promoter and other regulatory elements of DNA exposed after removal of histone core Chromatin remodelling can be induced by two separate mechanism; By histone modification:includes acetylation, methylation and phosphorylation Histone acetylation catalysed by histone acetyl transferase (HAT) and favours gene expression Histone deacetylation is catalysed by histone deacetylated enzyme (HDACs) and is always associated with gene repression

Post transcriptional gene regulation:

Splicing is the modification event of pre mRNA which occurs in nucleus just after transcription but before the RNA moves to the cytoplasm In RNA splicing non coding regions of pre mRNA called introns are removed and coding regions called exons are religated Removal of every intron requires two transesterification reactions: First transesterification reaction displaces exon from intron with 3' OH group Second transesterification reaction always catalysed by 3'OH group of displaced exon at 3' splice site

Translational gene regulation:

Eukaryotic translation is required for preparation of ribosomal small subunit which in turn require large number of initiation factors eIF2 facilitate transportation of initiating tRNA from cytosol to the P site of ribosomes eIF2α serves as key regulatory role in global protein synthesis and inhibits protein synthesis in response of cellular stress

Post translational gene regulation:

Post translational modifications includes phosphorylation or occurs by means of irreversible events (proteolysis) Post translational modifications play a fundamental role in regulating the folding of proteins, their targeting to specific subcellular compartments, their interaction with ligands or other proteins, and their functional state, such as catalytic activity in the case of enzymes or the signaling function of proteins involved in signal transduction pathways Phosphate moiety is covalently bound to an amino acid, phosphorylation occurs through the action of specific protein modifiers called kinases