Regulating Gene Expression from RNA to Protein
Gene Expression is
controlled at all of these
steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
A processed mRNA ready for translation
5’ untranslated
region
Protects from degradation
3’ untranslated
region
Protects from degradation/
transport
Gene Expression is
controlled at all of these
steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
Seeds germinated underground begin growing in
darkness then emerge into light and begin photosynthesis
energy from seed
energy from sun
The level of this mRNA increases after plants are
exposed to light.
•How might the cell accomplish this?
The level of this mRNA increases after plants are
exposed to light.
•How might the cell accomplish this?
Increased transcription and/or decreased mRNA
degradation
Northern blot analysis: The level of this mRNA
increases after plants are exposed to light.
•How might the cell accomplish this?
•Does this necessarily lead to increased protein
production?
Gene Expression is
controlled at all of these
steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
Fig 15.25
Regulation of
iron assimilation
in mammals:
Regulating of
Translation
Ferritin is regulated at translation
Fig 15.26
C. elegans is commonly used to study development
C. elegans development
C. elegans
mutants with
cells that do not
develop
properly.
C. elegans
mutants with
cells that do not
develop
properly.
The product of
these genes was
found to be
RNA?
MicroRNAs (miRNA) are ~22nt RNAs
that play important regulatory roles
Cell vol. 116,
281-297 2004
miRNA expressed
How do
microRNAs
control gene
expression?
Fig 15.23 and
miRNA
processed to
~22nt RNA
Mature miRNA
A processed mRNA ready for translation:
microRNAs inhibit translation by binding to the 3’ end of mRNA
microRNA bind to 3’-UTR
5’-UTR
3’-UTR
miRNA expressed
the 3’ end
with attached
microRNA
interacts with
the 5’ end,
blocking
translation
Fig 15.23 and
miRNA
processed to
~22nt RNA
Mature miRNA
miRNAs can lead to
methylation of DNA that
leads to inhibition of
transcription
microRNAs primarily target gene products that
function during development
Tbl 1
tissue specific
expression of mouse
microRNA
PNAS vol. 101 #1 pg 360-365, 2004
Silencing RNAs (siRNA) are artificially
induced dsRNA
Fig 15.21
siRNA with exact matches
to the target mRNA causes
degradation of the mRNA
microRNA
Translation inhibited
siRNA
mRNA degraded
Gene Expression is
controlled at all of these
steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 16.1
Phosphorylation and
dephosphorylation of
proteins can change
activity
Ubiquitinization targets proteins for degradation
All protein interactions in an organism compose the
interactome
Some proteins function in the cytoplasm; others need to be
transported to various organelles.
How can proteins be delivered to
their appropriate destinations?
Fig 13.23
Proteins are directed
to their destinations
via signals in the
amino acid sequence
Protein Destinations: secretion or membrane
• Signal sequences target proteins for secretion
Translation of secreted proteins
Translation of membrane bound proteins
Translation of secreted or membrane
bound proteins
This step determines secretion or
membrane bound.
Protein Destinations: nucleus Signal anywhere in protein,
Translation in cytoplasm,
Signal not removed
Protein Destinations: mitochondria or
chloroplast
Signal translated first, Translation in cytoplasm, Signal removed
Protein Destinations: signals in protein
determine destination
Tbl 13.8
Development: differentiating cells to become
an organism