DNA Binding proteins

We present here the comparison of two proteins known to bind to the DNA in two different organisms: the tryptophan repressor of E. Coli and CRO protein of phage 434. These two proteins bind tightly to the DNA at a gene's promoter, thus preventing RNA polymerase from fixing and hence blocking the initiation of the transcription (these are repressors). They should thus have a common substructure that realizes this biological function.

TRP Repressor of E. Coli

(104 Amino acids)

Cro protein of Phage 434

(65 Amino acids)

There also exists proteins that bind next to the promoter of a gene and help the polymerase to bind, thus assisting the transcription of the gene. They are called activators.

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