{"id":682,"date":"2023-04-02T18:10:11","date_gmt":"2023-04-02T18:10:11","guid":{"rendered":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/?post_type=chapter&p=682"},"modified":"2023-04-07T10:42:17","modified_gmt":"2023-04-07T10:42:17","slug":"eukaryotic-transcription-gene-regulation","status":"publish","type":"chapter","link":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/chapter\/eukaryotic-transcription-gene-regulation\/","title":{"raw":"Eukaryotic Transcription gene regulation","rendered":"Eukaryotic Transcription gene regulation"},"content":{"raw":"

Transcriptional Regulation in Eukaryotes<\/h1>\r\nThere are three classes of control elements in eukaryotes:\r\n
\u2022The RNA polymerase II binding region (the core promoter)<\/div>\r\n
\u2022 cis-acting binding sequences that bind to proteins with RNA polymerase affinity, which in turn help bind RNA polymerase to a promoter.<\/div>\r\n
\u2022A trans-acting DNA element<\/div>\r\n
cis-acting DNA element<\/span><\/strong><\/h6>\r\n
\r\n
\u2022These are short DNA sequences that acts as a binding site for a protein that has an affinity for that specific sequence.<\/div>\r\n
\r\n
include short consensus sequences<\/div>\r\n
\u2022 These elements\u00a0 are usually located within 200 bp upstream of the transcription initiation site<\/div>\r\n
\u2022They can be included in a promoter or an enhancer<\/div>\r\n
\u2022 They have an affinity for a specific protein that binds to it, serving as a regulator<\/div>\r\n<\/div>\r\n
\u2022The term \"cis acting\" means that the bound protein acts only upon DNA sequences on the same DNA molecule as the cis-acting sequence.<\/div>\r\n
\u2022These are also found in prokaryotes example ; the operator of the lac operon.<\/div>\r\n<\/div>\r\n
<\/div>\r\n

cis-acting DNA elements-\u00a0enhancers and silencers<\/strong><\/h2>\r\n
\r\n\r\n\u2022An enhancer DNA sequence (or positive regulatory element) turns a gene ON.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022When the activator is bound to the enhancer, RNA polymerase is more highly attracted to the gene.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022enhancers are located upstream or downstream of the promoter region,\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022Multiple regulatory proteins bound to binding sites in an enhancer can form a large, complex enhancesosome that has varying affinity for RNA polymerase, depending on its size and exact composition.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022The enhanceosome can both recruit additional co-activators and facilitate chromatin remodeling.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022A silencer DNA sequence (or negative regulatory element) turns a gene OFF or reduces its rate of transcription.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022When the repressor is bound to the silencer, RNA polymerase cannot attach and transcribe the gene.\r\n\r\n<\/div>\r\n
\r\n\r\n\u2022silencers are located downstream of a promoter.\r\n\r\n<\/div>\r\n

Trans-acting DNA element<\/h1>\r\n
\u2022A trans-acting DNA element is a DNA sequence that codes for a protein (a trans-acting factor) that controls the expression of a gene at a separate location by binding to its cis-acting element.<\/div>\r\n\u00a0Trans-acting factors:<\/strong>\r\n
\u2022 These are enzymes that interact with RNA polymerase<\/div>\r\n
\u2022 They bind to RNA polymerase to stabilize the initiation complex<\/div>\r\n
\u2022 They may bind to a few promoters and serve as positive regulators<\/div>\r\n
\u2022A trans-acting factor can affect the expression of genes located on separate chromosomes.<\/div>\r\n
\r\n

Post-Translational Control of Gene Expression<\/h2>\r\n