Problem
You are studying the regulation of crystallin alpha A (CRYAA) which is part of the crystallins, important structural proteins in the vertebrate lens (eye). You use a reporter assay and put the upstream region of the CRYAA gene upstream of the coding region for luciferase (your reporter gene). You then experimentally delete 3 different segments of the upstream region and measure their effects on expression of luciferase. Given the listed transcription levels (%) in the table below, what are the most likely cis-acting elements of the CRYAA gene that have been deleted in each segment? Explain how you came to your conclusions.
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Expression level
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Wild-type (no deletion)
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100%
|
|
Deleted segment 1
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300%
|
|
Deleted segment 2
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0%
|
|
Deleted segment 3
|
63%
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Note, expression levels are normalized to wild-type (no deletions); wild-type will always be 100%. For instance something with 50% transcription levels would have ½ of the transcription levels of wild-type.