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Repressor protein

Definition

noun, plural: repressor proteins

A protein in which its binding to the operator inhibits the transcription of one or more genes


Supplement

Repressor proteins can be DNA- or RNA-binding:

  • DNA-binding repressors - block the binding of RNA polymerase to the promoter. As a result, the gene is prevented from being transcribed into mRNA
  • RNA-binding repressors - bind to mRNA, preventing protein translation

Examples of repressor proteins are lac repressor that inhibits the expression of lac operon in E. coli. Another is MetJ, a methionine repressor of met operon.

Repressor proteins are influenced by the presence of other molecules, such as corepressors and inducers. Corepressors are molecules that bind and activate repressors. Inducers, on the other hand, bind and regulate repressors by inducing the latter to undergo conformational change thereby decreasing binding affinity to the operator.


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mRNA transcripts, cis/trans-acting questions

... (The mutations are present only on copies labeled as m1 or m2.) Protein A produced? Protein B produced? Genotype no induction with induction ... d. probably a loss-of-function mutation in the gene encoding a repressor to the operon?

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by animus31
Fri Nov 09, 2012 11:58 am
 
Forum: Genetics
Topic: mRNA transcripts, cis/trans-acting questions
Replies: 0
Views: 2133

DIFFERENT BETWEEN REPRESSOR AND INDUCER

CAN ANY BODY HELP ME TO UNDERSTAND BASIC DIFFERENT BETWEEN REPRESSOR AND INDUCER. AND WHAT IS THE DIFFERENT BETWEEN INDUCER AND ACTIVATOR PROTEIN IN RESPECT TO OPERONS ??

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by Helics
Wed Oct 17, 2012 3:23 pm
 
Forum: Molecular Biology
Topic: DIFFERENT BETWEEN REPRESSOR AND INDUCER
Replies: 1
Views: 2877

Re: Yeast Mating Type Switching

... is due to the preferential accumulation of an unstable transcriptional repressor protein, Ash1p, in daughter cell nuclei. Here it is shown thatASH1 messenger RNA (mRNA) preferentially ...

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by fiona1985
Mon Aug 15, 2011 10:30 am
 
Forum: Cell Biology
Topic: Yeast Mating Type Switching
Replies: 3
Views: 6245

Repressor always bound to operator

In a normally functioning lac operon, in prokaryotes, repressor protein binds the operator only when lactose concentration is high. However, consider a mutant where ...

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by amoeba271
Tue Nov 24, 2009 6:00 am
 
Forum: Molecular Biology
Topic: Repressor always bound to operator
Replies: 2
Views: 1790

Cis and Trans Elements of Operon?

... DNA strand(of course it can still be, it just isn't a requirement). The repressor gene acts in trans. It doesn't really matter where it is located, as long as it makes the repressor protein. Cheers. BTW, are you by any chance taking an intro molecular biology college ...

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by MrMistery
Tue Nov 18, 2008 11:05 pm
 
Forum: Molecular Biology
Topic: Cis and Trans Elements of Operon?
Replies: 4
Views: 6957
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