Question

A transcription factor “T” is a critical regulator of the expression of the gene “G”. “T” works as a dimer and normally resides in the cytoplasm until the small protein signal molecule “P” is bound to it. When “P” is bound to “T” the transcription factor is moved to the nucleus and can regulate the expression of the gene “G”. Explain what would be the expression of the gene “G” if:

A) There is a mutation in “T” that removes part of the DNA binding domain

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B) There is a mutation in “T” that removes part of dimerization domain

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C) There is a mutation in “T” that removes the “P” binding site

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D) The small protein signal molecule “P” is present in the cytoplasm of the cell in all cases.

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Answer 1

A) If there is mutation in T that removes part of DNA binding domain,there won't be much effect,binding will happen and thus gene(G) is expressed.Because domains are structure which are little bit flexible.

B)If there is mutation in T that removes part of dimerisation site,dimerisation still happens and gene (G)gets expressed.Because expression of genes depends on movement of TF(T) into nucleus.

C) If there is mutation in T that removes P binding site,T cannot binds to P then dimerisation won't happens.So TF don't work.So no gene expression.

D)Then gene G is expressed all the time.