Transcript Regulation of gene expression

Regulation of gene expression
Haixu Tang
School of Informatics
Genetic material are not lost
Different Cell Types Synthesize
Different Sets of Proteins
• Many processes are common to all cells, and any two cells in a
single organism therefore have many proteins in common.
• Some proteins are abundant in the specialized cells in which they
function and cannot be detected elsewhere, even by sensitive tests.
Hemoglobin, for example, can be detected only in red blood cells.
• Studies of the number of different mRNAs suggest that, at any one
time, a typical human cell expresses approximately 10,000 20,000 of
its approximately 30,000 genes
• Although the differences in mRNAs among specialized cell types are
striking, they nonetheless underestimate the full range of differences
Gene Expression is regulated in
Response to External Signals
Switching devices for gene
regulation
• Short stretches of DNA of defined
sequence (cis-elements)
• gene regulatory proteins that recognize
and bind to them (trans-factors)
Base pairs in DNA can be
recognized from their edges
DNA conformation changes after
protein binding
Bacteria
Yeast
Drosophila
Mammals
lac repressor
5 AATTGTGAGCGGATAACAATT
CAP
TGTGAGTTAGCTCACT
lambda repressor
TATCACCGCCAGAGGTA
Gal4
CGGAGGACTGTCCTCCG
Mata2
CATGTAATT
Gcn4
ATGACTCAT
Kruppel
AACGGGTTAA
Bicoid
GGGATTAGA
Sp1
GGGCGG
Oct-1 Pou domain
ATGCAAAT
GATA-1
TGATAG
MyoD
CAAATG
p53
GGGCAAGTCT
DNA binding on the major groove
The DNA-binding helix-turn-helix
motif
Some helix-turn-helix DNAbinding proteins
lambda Cro protein
Hemeodomain
Zinc fingers
DNA binding by a zinc finger
protein
A dimer of the zinc finger domain
b sheets Can Also Recognize DNA
Leucine Zipper
Heterodomain of Leucine zipper
Dimerization of HTH
A heterodimer composed of two
homeodomain
DNA-protein interaction
DNA
recognition
code
Gel-mobility assay
DNA affinity chromatography
Tryptophan switch
Switch on/off
Switch on/off by tryptophan binding
Dual control of the lac operon
Enhancers from distance
Binding of two proteins to separate sites
on the DNA double helix can greatly
increase their probability of interacting
Protein interaction in gene switch
Gene control region for a
eukaryotic gene
The modular structure of a gene
activator protein
Transcriptional synergy
Repressor
Assembled complex
The nonuniform space
distribution
Switching gene expression by
DNA inversion in bacteria.
Control of cell type in yeast
Cassette model of yeast matingtype switching
Speculative model for the
heterochromatin
A positive feedback loop
Circadian clock
Clustered genes coordinated by
single protein
Myogenic regulatory proteins in
muscle development
ey gene in precursor cells of the leg
X-inactivation
DNA methylation patterns are
faithfully inherited
Genome imprinting
CG island
An explanation of CG island
Post transcriptional
regulation
Alternative splicing
Negative and positive control of
alternative RNA splicing
Regulation of the site of RNA
cleavage
RNA editing in the mitochondria
of trypanosomes
Mechanism of A-to-I RNA editing
in mammals
Negative translational control
The elF-2 cycle
Translation initiation
mRNA decay
The competition between mRNA
translation and mRNA decay
Two posttranslational controls
mediated by iron
Nonsense mRNA decay