mcb 317 genetics and genomics mcb 317 topic 10, part 3 a story of transcription
TRANSCRIPT
MCB 317Genetics and Genomics
MCB 317 Topic 10, part 3A Story of Transcription
Why are Acitvators cartooned as two balls held together by a tether?
Co-activators & chromatin remodeling complexes not shown
General FactorsRNAP
Activators
Properties of Activators
ActivatorsMultiple functions = multiple domains
• DNA binding domain• Activation domain• Dimerization domain (some)• Ligand binding domain (some)
Genes in Yeast vs. Larger Euk
Reporter gene in yeast -> use to study activators
Deletion Analysis of Coding Region -> Truncated Proteins
Domains of Activators
Properties of Activators:Transcription factor families
Gene Families
• It is more common to create variations of a useful protein structure than it is to create a new structure
• Families created by gene duplication and divergence
Gene Families are Generated by Duplication and Divergence
ActivatorsMultiple functions = multiple domains
• DNA binding domain• Activation domain• Dimerization domain (some)• Ligand binding domain (some)
• Helix-turn-helix• Helix-loop-helix• Homeobox• Zinc finger• Leucine zipper
Activators classified based on their DNA binding domain: Transcription factor families
Activators classified based on their DNA binding domain: Transcription factor families
Different Family Members = Different Binding Site
Protein Domains andStructural Motifs
Protein – DNA interaction
General Properties of Proteins that bind DNA
Helix-turn-helix
Homeodomain
Zinc finger type I structure
LeucineZipper
Activators (factors) that dimerize only bind DNA as dimers
Homodimers bind inverted repeats
Homodimers, Heterodimers, Family Members and Recognition Sites
Zinc-finger type II Heterodimers
Helix-loop-helix dimer
Cell Type Specific Patterns of Txn = Combination of Which Receptors and Txn Factors (Activators) a Cell Produces
Some Key Activators -> Txn of other Activators
ActivatorsMultiple functions = multiple domains
• DNA binding domain• Activation domain• Dimerization domain (some)• Ligand binding domain (some)
Gene family members
Gene Gene
Gene
Ortholog
Paralog
Orthologs = family members in different speciesParalogs = family members in same species
Blast Search
Yeast = 34 Zinc Finger Txn Factors (Activators)
Ab
Protein
ExpressionPattern
Gene
Gene (Organism 2)Paralogs
Mutant Gene
Biochemistry
Genetics
Mutant Organism
1
2
3
4
78
56 9
10
11
Orthologs and Paralogs
9
Many Types of Steroid Hormones
A Variety of Family Members of Steroid-binding Txn Factors (Activators)
In General Family Members have similar properties:Monomer v. dimer, mode of activation/inhibition, even types of genes regulated: homeodomains -> genes invovled in development
Gene Families
• It is more common to create variations of a useful protein structure than it is to create a new structure
• Families created by gene duplication and divergence