Transcriptional Regulation: Control by; - a regulatory region of DNA, sequences - gene regulatory proteins Fig.9-3 Double-helical structure of DNA, major and minor grooves on the outside of DNA Fig.9-9 The binding of a gene regulatory protein to the DNA major groove

Fig.9-10 The DNA-binding helix-turn-helix motif, A.carboxyl-terminal called recognition helix. B. helix fits into the DNA major groove Fig.9-11 Some helix-turn-helix DNA-binding proteins. All of the proteins bind DNA as dimers A. B.

Fig.9-18 A leucine zipper dimer bound to DNA. Fig.9-19 Heterodimerization of leucine zipper proteina can alter their DNA-binding specificity. - 1&2= homodimers bind to symmetric DNA sequences - 3= two diff. Monomer combine to form a heterodimer

Fig.9-23 DNA affinity chromatography

Eucaryotic Transcriptional Regulation: Transcription Controls: 1. Gene Control Region 2. Gene Activator Protein 3. Gene Repressor Protein 4. Gene Regulatory Protein 5. DNA Methylation Post-Transcription Controls: 1. Transcription Attenuation 2. Alternative RNA Splicing 3. Changed Site of RNA Transcript Cleavage 4. RNA Editing

Transcription Controls: 1. Gene Control Region - initiate gene transcription - regulate the rate at which initiation occur - GCR consists of Promoter, Regulatory sequence

Transcription Controls: 2. Gene Activator Protein - accelerate the assembly of General Transcription Factors

Fig The modular structure of a gene activator protein, activation domain & DNA-binding domain

Fig One model to explain the displacement of nucleosomes during the initiation of transcription in euc.

Transcription Controls: 3. Gene Repressor Protein - Inhibit transcription in various ways

Transcription Controls: 4. Gene Regulatory Protein - proteins form complexes for creating elaborate switches to control transcription Fig Euc. Gene regulatory proteins often assemble into small complexes on DNA. A. nature & function of the complexes, form depending on the specific DNA seq. B. one complex activates gene transc., another represses transcription.

Fig Some ways in which the activity of gene regulatory proteins is regulated in eucaryotic cells.

Transcription Contrils: 5. DNA Methylation - inhibit transcription

Fig.9-70 The CG islands surrounding the promoter in three mammalian housekeeping genes. - CG islands, ~40,000 genes - ~1,000-2,000 nts. Pairs long - surrounding the Pormoters, called housekeeping genes, demethylated

Post-Transcription Controls: - operate after RNA Pol has bound to the gene’s Promoter and begun RNA synthesis. 1. Transcription Attenuation 2. Alternative RNA Splicing 3. Changed Site of RNA Transcript Cleavage 4. RNA Editing

Post-Transcription Controls: 1. Transcription Attenuation In Bacteria: By - antitermination factors - switch the Sigma factors

Post-Transcription Controls: 2. Alternative RNA Splicing - produce different forms of mRNA Optional exon Optional intron Mutually exclusive exons Internal splice site

Fig.9-74 Negative and Positive Control of Alternative RNA Splicing. A. Negative Control, Repressor Protein binds to the primary RNA tranc. B. Positive Control, splicing machinery unable to remove a intron without an activator protein.

Post-Transcription Controls: 3. Changed Site of RNA Transcript Cleavage

Post-Transcription Controls: 4. RNA Editing