Analyze the Data 9-2: DNA Binding with EMSA An electrophoretic mobility shift as

Question

Analyze the Data 9-2: DNA Binding with EMSA

An electrophoretic mobility shift assay (EMSA) was performed using a radiolabeled DNA fragment from the sequence upstream of gene X. This DNA probe was incubated with (+) or without (-) nuclear extract isolated from tissues A (bone); B (lung); C (brain); and D (skin). The DNA;protein complexes were then fractionated on nondenaturing polyacrylamide gels. The gels were exposed to autoradiographic film; the results are presented in the figure.

If gene X is transcribed in lung and brain tissue but not in bone and skin tissue, what type of transcription factor is the binding activity? Speculate as to the identity of other factors that might be associated at the gene X promoter in bone and skin tissue.

Explanation / Answer

From the given gel, it is clear that gel shift is seen only in nuclear extracts from bone and skin tissues. This shows that a transcription factor is present specifically in these tissues. It is given that these tissues do not express gene X. So, the transcription factor in bone and skin tissues must be a negative regulator. i.e. repressor of gene X transcription. Since this transcription factor is absent in lung and brain tissues, gene X is expressed in these tissues.

The speculated transcription factor might recruit transcription silencing complex (could be epigenetic) to the promoter region of gene X. This leads to the repression of gene X expression.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.