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Gene Expression. AKA Molecular Biology. Gene Expression Le Dogma Centrale. Genome Organization. Gene Structure. Transcription. Post-transcriptional Modification. Translation. Post-translational Modification. Regulatory Sequences. Transcription.
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Gene Expression AKA Molecular Biology
Transcription • Just 3 little words that aren't that hard to say: • Initiation • Elongation • Termination
Classes of mRNA • Abundant Class – Simple mRNA Fraction • 1- 5 different genes (transcripts) which represent >50% of total mRNA expressed in cell/tissue • 1,000 - 100,000 copies of each mRNA/cell • Moderate Class • 5-50 different genes (transcripts) which represent 10-20% of total mRNA expressed in cell/tissue • 10 -100 copies of each mRNA/cell • Rare Class – Complex mRNA Fraction • >100 different genes (usually 10-20K genes) which represent 10%-20% of the total mRNA expressed in a cell/tissue • 1-10 copies of each mRNA/cell
Functional Domains of Eukaryotic Transcription Factors • DNA binding domain – DBD • Binds specific sequence of base pairs • Transcriptional activation domain – TAD • Interacts with basal txn factors or directly with RNA polymerase II • Protein-protein interaction domain – PPID • Homo- & Hetero dimerization domains • Interaction with other txn factors (besides the basal apparatus)
Transcription Factor Families Family Representative Homeodomain Hox Hoxa-1, Antp, eve, en POU Pit-1,Unc-86, Oct-2, Brn-5 LIM Lim-1, Isl-1 Paired Box Pax-1,2,6, Prd Forkhead/Winged Helix Fkh, HNF-3 Basic helix-loop-helix MyoD, Ac, da, emc AP1, Myc, C/EBP leucine-zipper Zinc-finger monomeric WT-1, Krox-20, Kr, hb steroid receptors GR, ER, RAR, kni Sox Sry, SoxD, Sox2 MADS box MEF-1, MCM-1, AG, DEF, SRF
Homeodomain First Identified in Genes Causing Homeotic Transformations Antennapedia Ultrabithorax