Regulation of gene expression

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Regulation of Gene Expression
R.C. Gupta Professor and Head Dept. of
Biochemistry National Institute of Medical
Sciences Jaipur, India
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A large number of genes are present in DNA
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Most of them encode proteins some encode tRNA
and rRNA
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Points for regulation of gene expression
Gene
Control point
hnRNA
Control point
mRNA (in nucleus)
Control point
mRNA (in cytosol)
Control point
Protein
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Regulation in prokaryotes
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Jacob
Monod
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Jacob and Monod conducted their study in E.coli
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Operon
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Regulation in eukaryotes
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EMB-RCG
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Gene amplification
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Amplification of
dihydrofolate reductase gene has been seen in
cancer cells on administration of amethopterin
Amethopterin is a competitive inhibitor of
dihydrofolate reductase
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Gene re-arrangement
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Regulation of transcription
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EMB-RCG
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Enhancer elements
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Silencer elements
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Hormone response elements
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The gene influenced by the hormone is preceded by
a hormone-response element
The receptor-hormone complex binds to the
hormone-response element
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This increases the transcription of the
downstream structural gene
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Hormone-response element (HRE) is the binding
site for hormone-receptor complex
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Heat shock elements
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Promoters
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mRNA stability
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Alternative splicing
The primary transcript (hnRNA) can be spliced
in different ways
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By joining different exons, different proteins
can be formed
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hnRNA of tropomyosin is spliced in different
ways in different tissues
This results in the formation of different
tropomyosins in different tissues
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RNA editing
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Protein-DNA interaction
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Helix-turn-helix motif
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Zinc finger motif
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Leucine zipper motif
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