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10.3 Eukaryotic gene control: purposes
and general principles
 Unlike bacterial cells and most single cell eukaryotes, cells in
multicelular organisms have relatively few genes that are
reversibly regulated by environmental conditions
 However, gene control in multicellular organisms is important
for development and differentiation, and is generally not
reversible
Copyright (c) by W. H. Freeman and Company
10.3 Many genes in higher eukaryotes are
regulated by controlling their transcription
The nascent chain (run-on)
assay allows measurement
of the rate of transcription of
a given gene
Figure 10-22
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10.3 Differential synthesis of 12 mRNAs
encoding liver-specific genes
Figure 10-23
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10.3 Regulatory elements in eukaryotic DNA
often are many kilobases from start sites
 The basic principles that control transcription in bacteria also
apply to eukaryotic organisms: transcription is initiated at a
specific base pair and is controlled by the binding of transacting proteins (transcription factors) to cis-acting regulatory
DNA sequences
 However, eukaryotic cis-acting elements are often much
further from the promoter they regulate, and transcription
from a single promoter may be regulated by binding of
multiple transcription factors to alternative control elements
 Transcription control sequences can be identified by analysis
of a 5-deletion series
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10.3 Construction and analysis of a 5-deletion
series
Figure 10-24
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10.3 Analysis of labeled nascent transcripts
allows mapping of the transcription-initiation site
Figure 10-28
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10.3 RNA polymerase II initiates transcription at DNA
sequences corresponding to the 5 cap of mRNAs
“Runs off”
“Runs off”
“Runs off”
Figure 10-29
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10.4 The TATA box is a highly conserved
promoter in eukaryotic DNA
Alternative promoters in eukaryotes include initiators and CpG islands
5’-YYA+1N-T/A-YYY-3’ (Y=C/T)
Figure 10-30
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10.4 Identification of transcription-control
elements with linker mutants
Figure 10-31
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10.4 Promoter-proximal elements help
regulate eukaryotic genes
Figure 10-32
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10.4 Transcription by RNA polymerase II
often is stimulated by distant enhancer sites
Identification of the SV40 enhancer region
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Figure 10-33
10.4 Most eukaryotic genes are regulated by
multiple transcription control mechanisms
Figure 10-34
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10.5 Transcription factors may be identified
by biochemical techniques
Figure 10-35
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10.5 In vivo assay for transcription factor activity
Figure 10-37
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10.5 A series of Gal4 deletion mutants demonstrated
that transcription factors are composed of separable
DNA-binding and activation domains
Figure 10-38
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10.5 Transcriptional activators are modular proteins
composed of distinct functional domains
Figure 10-39
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10.5 DNA-binding domains can be classified
into numerous structural types
 Homeodomain proteins
 Zinc-finger proteins
 Winged-helix (forkhead) proteins
 Leucine-zipper proteins
 Helix-loop-helix proteins
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10.5 Homeodomain from Engrailed protein interacting
with its specific DNA recognition site
Figure 10-40
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10.5 Interactions of C2H2 and C4 zinc-finger
domains with DNA
Figure 10-41
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10.5 Interaction between a C6 zinc-finger
protein (Gal4) and DNA
Figure 10-42
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10.5 Interaction of a homodimeric leucine-zipper
protein and DNA
dimerização assegurada pela interacção dos
a.a. Hidrofóbicos (ex:leucina) espaçados
regularmente
Figure 10-43
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10.5 Interaction of a helix-loop-helix in a
homodimeric protein and DNA
Figure 10-44
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10.5 Heterodimeric transcriptional factors
increase gene-control options
Figure 10-45
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10.5 Activation domains exhibit considerable
structural diversity
Figure 10-47
Figure 10-46
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10.5 Multiprotein complexes form on enhancers
Figure 10-48
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10.5 Many repressors are the functional
converse of activators
 Eukaryotic transcription is regulated by repressors as well as
activators
 Repressor-binding sites can be identified and repressors
purified by the same techniques used for activators
 Many eukaryotic repressors have two domains: a DNAbinding domain and a repressor domain
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10.6 RNA polymerase II transcriptioninitiation complex
 Initiation by Pol II requires general transcription factors, which
position Pol II at initiation sites and are required for
transcription of most genes transcribed by this polymerase
 General transcription factors are multimeric and highly
conserved
 Proteins comprising the Pol II transcription-initiation complex
assemble in a specific order in vitro but most of the proteins
may combine to form a holoenzyme complex in vivo
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10.6 Stepwise assembly of Pol II
transcription-initiation complex in vitro
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Figure 10-50
10.6 The conserved C-terminal domain of
TBP binds to TATA-box DNA
TBP is a subunit of TFIID
Figure 10-51
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10.6 Structural model of the complex of
promoter DNA, TBP, TFIIB, and Pol II
Figure 10-53
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10.7 Activators stimulate the highly
cooperative assembly of initiation complexes
Binding sites for activators that control transcription of the mouse TTR gene
Figure 10-60
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10.7 Model for cooperative assembly of an activated
transcription-initiation complex in the TTR promoter
Figure 10-61
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10.7 Repressors interfere directly with
transcription initiation in several ways
Figure 10-62
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10.7 Lipid-soluble hormones control the
activities of nuclear receptors
Figure 10-63
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10.7 Domain structure of nuclear receptors
Figure 10-64
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10.7 Response elements are DNA sites that
bind several major nuclear receptors
Figure 10-65
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10.7 Model of hormone-dependent gene
activation by the glucocorticoid receptor
Figure 10-67
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10.7 Polypeptide hormones signal
phosphorylation of some transcription factors
Model of IFN-mediated
gene activation by
phosphorylation and
dimerization of Stat1
Figure 10-68
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10.8 Transcription initiation by Pol I and
Pol III is analogous to that by Pol II
Figure 10-69
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10.8 Other transcription systems
 T7 and related bacteriophages express monomeric, largely
unregulated RNA polymerases
 Mitochondrial DNA is transcribed by RNA polymerases with
similarities to bacteriophage and bacterial enzymes
 Transcription of chloroplast DNA resembles bacterial
transcription
 Transcription by archaeans is closer to eukaryotic than to
bacterial transcription
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