Which tissues contain a binding activity that recognizes the sequence upstream of gene X? Is the transcription factor the same in each tissue?

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.

 

  1. Which tissues contain a binding activity that recognizes the sequence upstream of gene X? Is the transcription factor the same in each tissue?
  2. If the binding activity was purified, what test could be done to verify that this factor is in fact a transcription factor?
  3. What type of assay would be performed to determine the specific DNA sequence(s) within this probe that the transcription factor binds?
  4. 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.