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Unformatted text preview: 1 Lecture 21: Eukaryotic Gene Regulation I March 5, 2008 Today ’ s Outline 1. DNA binding proteins – proks and euks 2. Overview of euk gene expression 3. Chromatin organization Announcements Make-up Policy on Quizzes: 1) excused absence, 2) make up quiz within one week, 3) go to ANY GSI’s office hours Biology 172 Review of lac Operon repressor lac tose CAP-cAMP Binding sites in the lac operon Operator • Many nucleotide sequences that bind proteins have two-fold rotational (dyad) symmetry • Lac Repressor protein binds O 1 and one of the other two sites O 2 or O 3 5’ 3’ 3’ 5’ Helix-Turn-Helix Motifs in DNA-Binding Proteins Secondary & Tertiary Protein Structure Quaternary Structure of the Lac Repressor Protein … to the lac operon Operator • DNA forms loops that bring protein binding sites physically closer together • Each half of the symmetrical Operator sequence is bound by a helix- turn-helix DNA binding motif in one subunit of the Repressor protein 2 Conformational change when Inducer (lactose) binds Repressor (protein) of the lac operon Active form Inactive form Major Types of DNA Binding Protein Motifs in Eukaryotes • Bind to major groove of DNA helix • Binding involves many types of intramolecular bonds >> together provide very specific and strong binding interaction Eukaryotic Gene Regulation...
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This note was uploaded on 12/06/2009 for the course BIO 172 taught by Professor Clark during the Winter '08 term at University of Michigan.
- Winter '08