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Regolazione del metabolismo
Controllo dell’attività degli enzimi chiave:
Regolazione allosterica (controllo della cinetica)
Modificazioni post-traduzionali (ON/OFF)
Regolazione dell’espressione dei geni degli
enzimi del metabolismo e dei loro regolatori
REGOLAZIONE DELL’ESPRESSIONE GENICA
SEGNALI EXTRACELLULARI
Controllo
dell’attività
trascrizione
GENE
traduzione
mRNA
degradazione
degradazione
STATO DELLA CELLULA
ENZIMA
REGOLAZIONE DELL’ESPRESSIONE GENICA
SEGNALI EXTRACELLULARI
Controllo
dell’attività
trascrizione
GENE
traduzione
mRNA
PROTEINA
degradazione
degradazione
I. Regolazione della trascrizione
I nutrienti sono regolatori della trascrizione
Figure 10-2
Experimental evidence for trans-acting
genes/proteins
Experimental evidence for cis-acting DNA
sequences
The lac control region contains three critical
cis-acting sites
Figure 10-9
10.2 RNA polymerase binds to specific
promoter sequences to initiate transcription
Each subunit has a specific function
Figure 10-10
10.2 Differences in E. coli promoter sequences
affect the frequency of transcription initiation
Figure 10-11
10.2 Most bacterial repressors are dimers
containing  helices that insert into adjacent major
grooves of operator DNA
Figure 10-13
10.2 Ligand-induced conformational changes
alter affinity of many repressors for DNA
Tryptophan binding
induces a
conformational change
in the trp aporepressor
Figure 10-14
Positive control of the lac operon is exerted
by cAMP-CAP
CAP = catabolite
activator protein
10.2 Cooperative binding of cAMP-CAP and RNA
polymerase to the lac contol region activates
transcription
Figure 10-17
10.2 A space-filling model of cAMP-CAP
bound to lac promoter DNA
Figure 10-18
Glucosio
X
Pancreas
endocrino
Insulina
Glucagone
Glucosio
Glucosio
Glicogeno
Trigliceridi
Fegato
Tessuto adiposo
10.7 Model for cooperative assembly of an
activated transcription-initiation complex in the
TTR promoter
Figure 10-61
10.6 Stepwise assembly of Pol II
transcription-initiation complex in vitro
Figure 10-50
10.5 Transcriptional activators are modular proteins
composed of distinct functional domains
Figure 10-39
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
10.5 Homeodomain from Engrailed protein
interacting with its specific DNA recognition site
Figure 10-40
10.5 Interactions of C2H2 and C4 zinc-finger
domains with DNA
Figure 10-41
10.5 Interaction of a helix-loop-helix in a
homodimeric protein and DNA
Figure 10-44
10.5 Activation domains exhibit considerable
structural diversity
Figure 10-46
Figure 10-47
ISTONI
Figure 4-25 Molecular Biology of the Cell (© Garland Science 2008)
ASSEMBLAGGIO
DEL NUCLEOSOMA
Figure 4-26 Molecular Biology of the Cell (© Garland Science 2008)
Figure 4-27 Molecular Biology of the Cell (© Garland Science 2008)
Figure 4-31 Molecular Biology of the Cell (© Garland Science 2008)
Compattamento di Nucleosomi
Figure 4-35 Molecular Biology of the Cell (© Garland Science 2008)
MODIFICHE DEGLI ISTONI
Figure 4-38 Molecular Biology of the Cell (© Garland Science 2008)
Figure 4-44a Molecular Biology of the Cell (© Garland Science 2008)
Figure 4-39b Molecular Biology of the Cell (© Garland Science 2008)
EU- ed ETERO-CROMATINA
3. ACCESSO AL DNA
Interazione di Proteine con Istoni:
Cromo- e Bromo-domìni
Figure 7-49 Molecular Biology of the Cell (© Garland Science 2008)
Figure 7-47 (part 1 of 4) Molecular Biology of the Cell (© Garland Science 2008)
Figure 7-47 (part 2 of 4) Molecular Biology of the Cell (© Garland Science 2008)
Figure 7-47 (part 3 of 4) Molecular Biology of the Cell (© Garland Science 2008)
Figure 7-47 (part 4 of 4) Molecular Biology of the Cell (© Garland Science 2008)