You are interested in studying the transcriptional regulation of Glp1 promoter. This gene contains a binding site for two proteins A and B. Proteins A and B cannot bind to the DNA at the same time due to steric interference caused by a slight overlap in their binding sites. The binding sites of protein A and protein B can be seen in the figure below. Protein A binds to Site C and Protein B binds to site D. To assess whether either A or B have an influence on Glp1 expression, you create mutations in the DNA that selectively remove the non-overlapping sequences of binding site C or binding site D. You then examine Glp1 mRNA production within adult liver cells. You receive the following data. Experiment number Binding site C Binding site D Glp1 mRNA levels 1 + + high 2 + - high 3 - + none 4 - - none += binding site present, -= binding site absent What does this data tell us about which protein is bound during the normal situation (eg. Experiment 1)? What is protein A an enhancer or a repressor?
Gene Interactions
When the expression of a single trait is influenced by two or more different non-allelic genes, it is termed as genetic interaction. According to Mendel's law of inheritance, each gene functions in its own way and does not depend on the function of another gene, i.e., a single gene controls each of seven characteristics considered, but the complex contribution of many different genes determine many traits of an organism.
Gene Expression
Gene expression is a process by which the instructions present in deoxyribonucleic acid (DNA) are converted into useful molecules such as proteins, and functional messenger ribonucleic (mRNA) molecules in the case of non-protein-coding genes.
Transcriptional regulation
You are interested in studying the transcriptional regulation of Glp1 promoter. This gene contains a binding site for two proteins A and B. Proteins A and B cannot bind to the DNA at the same time due to steric interference caused by a slight overlap in their binding sites. The binding sites of protein A and protein B can be seen in the figure below. Protein A binds to Site C and Protein B binds to site D.
To assess whether either A or B have an influence on Glp1 expression, you create mutations in the DNA that selectively remove the non-overlapping sequences of binding site C or binding site D. You then examine Glp1 mRNA production within adult liver cells. You receive the following data.
|
Experiment number |
Binding site C |
Binding site D |
Glp1 mRNA levels |
|
1 |
+ |
+ |
high |
|
2 |
+ |
- |
high |
|
3 |
- |
+ |
none |
|
4 |
- |
- |
none |
+= binding site present, -= binding site absent
- What does this data tell us about which protein is bound during the normal situation (eg. Experiment 1)?
- What is protein A an enhancer or a repressor?
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