Download 5-9 bp

Ways to Regulate Transcription
Alternate sigma factor usage: controls selective transcription
of entire sets of genes
vegetative
(principal s)
s70
‫צמיחה‬
heat shock
nitrogen
starvation
+1
(16-19 bp)
TTGACA
s32
s60
TATAAT
(5-9 bp) A
+1
CNCTTGA
(13-15 bp) CCCATNT (5-9 bp) A
+1
CTGGNA (6 bp) TTGCA
(5-9 bp) A
!19.6.2008 – ‫התרגיל ביום חמישי זה‬
‫טרנסקריפציה באוקריוטים‬
Pre-mRNA
* microRNAs (miRNA) RNA molecules of about 21–23 nucleotides in length, which regulate gene
expression. are processed from primary transcripts known as pri-miRNA.
5’UTR
3’UTR
‫בתאי כבד בעכבר‬
RNA polymerase
‫מיקום ‪1+‬‬
‫יעילות ותדירות‬
‫רמה נמוכה (בזלית)‬
‫אינטרונים‬
‫‪E‬‬
‫‪S‬‬
‫‪RE‬‬
‫אין אחידות במיקום‬
‫וברצפי הבקרה בין גנים‬
‫שונים‪.‬‬
‫שלבי הטרנסקריפציה‬
Initiation •
Elongation •
Termination •
‫קומפלקס פרה‪-‬איניציציה‬
‫יציבות ותדירות‬
‫יצירת קומפלקס זה‬
‫קובעת את כמות וקצב‬
‫סינטזת ה‪RNA-‬‬
‫אופן אקטיבציה של טרנסקריפציה בתאים אוקריוטים‬
Stages in Initiation of Transcription
• Bacterial transcription
• Closed complex:
holoenzyme+promoter
• Open complex (DNA
melting, not need ATP)
• Abortive transcripton
• Productive initiation
– Transcribe past +9
– Sigma dissociates
• Elongation
• Eukaryotic
transcription
• Preinitiation complex
(PIC) assembly
• PIC activation (DNA
melting, needs ATP)
• Abortive transcription
• Productive initiation
– CTD phosphorylated
– Promoter clearance
• Elongation
initiation
Elongation
NTPs
TERMINATION
• RNA polymerase meets the terminator
• Terminator sequence: AAUAAA
• RNA polymerase releases from DNA
• Prokaryotes-releases at termination signal
• Eukaryotes-releases 10-35 base pairs after
termination signal
‫קומפלקס‬
‫האלונגציה‬
transcription
Transcription regulation
Gene expression
Gene expression
Basics of cell biology:development
Fertilized egg
Basics of cell biology:development
Cells differentiation
is due to different gene
Switches going on and off
These cells are different
because they express a
subset of their 24,000 genes
Promoter
Gene
To specify a new cell: place it in the right environment
or
EGF
Hedgehog
Wnt
Promoter
Gene
Retinoic acid
FGF
HGF
To specify a new cell: place it in the right environment
or
Substitute drugs/proteins for environment
Mophogens
Chromosome localization in
interphase
In interphase, chromosomes appear
to be localized to a sub-region of the
nucleus.