Experimental proof that most of the transcribed dna is bound to nucleosomes erythrocyte or oviduct cell Extract chromatin NAsc 1- sitive regions Digest with DNase I Percent maxlmum until 10 of DNA is binding of radioactive c NA Radioactive to DNA extracted DNase CDNA from treated Isolate DNA from chromatin chromatin Red blood cell DNA Globin cdNa Craln cell chromatin Globin CDNA 9400 Fibroblast chromatin+ Globin cDNA 9100 hybridize with probe Probe Red bood cell chromalin Globin cDnA hybridized Red Wood ell chromatin+ Ovalbumin cDNA 90-100 Stme After Weintraub and gnudine, 19?
Experimental proof that most of the transcribed DNA is bound to nucleosomes
The Histone H1 dependant conformation of nucleosomes inhibits the transcription of genes by packing adjacent nucleosomes together into tight arrays that prevent transcription factors and rna polymerases from gaining access to the genes
• The Histone H1 dependant conformation of nucleosomes inhibits the transcription of genes by packing adjacent nucleosomes together into tight arrays that prevent transcription factors and RNA polymerases from gaining access to the genes
Transcription factors Specifity and transcriptional enhancement Transcription factors are proteins that bind to the enhancer or promoter regions and interact such that transcription occurs from only a small group of promoters in any cell. In addition other proteins bind to the tad which have a Histone acety lase activity Histon Acetyl Transferases( HAT) Figure Histone Ac Hyperacetylation Alters Nucleosomal Conformation a nucleosome hypoacetylated histones NAc (blue)is more stable than a nucleosome with acetylated histones (yellow Acetylation renders the histone tails (black more mobile Ac
Transcription factors are proteins that bind to the enhancer or promoter regions and interact such that transcription occurs from only a small group of promoters in any cell. In addition other proteins bind to the TAD which have a Histone Acetylase activity = Histon Acetyl Transferases ( HAT ) Transcription factors Specifity and transcriptional enhancement
There appear to be certain transcriptional activators (such as the glucocorticoid receptor) that can bind to existing nucleosomes and disrupt them Once the nucleosomes are dissociated in the promoter region, other transcription factors can bind Nucleosome DNA is wound around a histone core, forming Initial TF binds TF binding to to a nucleosome part of the histone core Additional factors Histone h1 may bind the Other TFs T complex, further destabilizing the histone core When the histones have been displaced, other TFs mav 1g tao eQ Histone or carrier proteins
There appear to be certain transcriptional activators (such as the glucocorticoid receptor) that can bind to existing nucleosomes and disrupt them. Once the nucleosomes are dissociated in the promoter region, other transcription factors can bind
X Chromosome inactivation Males have Xy females have xX In both gender the amount of X-chromosome encoded gene products are the same There must be a down regulation of X-chromosome encoded genes in females
X Chromosome inactivation Males have XY Females have XX In both gender the amount of X-chromosome encoded gene products are the same There must be a down regulation of X-chromosome encoded genes in females