ou are researching the regulation of cell-size control and discover that a signaling pathway that acts through a particular enzyme-coupled receptor is important for the size growth (enlargement) of rat kidney cells. Receptor activation causes activation of adenylyl cyclase, which ultimately leads to the activation of PKA. PKA then phosphorylates a transcription factor called BTS on threonine 84. This phosphorylation is required to allow BTS to bind to specific regulatory DNA sequences, increasing the transcription of Zrt2, a gene encoding a protein vital for kidney cell growth. You find that kidney cells without this receptor are 25% smaller than normal cells. When you measure cells expressing a constitutively active version of PKA, you find they are 25% bigger than normal kidney cells. Based on these results, predict whether a kidney cell’s size would be bigger or smaller than normal kidney cells in each of the following circumstances. Explain why in 1-2 sentences for each. You add a drug that increases the activity of cyclic AMP phosphodiesterase. You mutate the cAMP-binding sites in the regulatory subunits of PKA, so that the complex binds cAMP more tightly.
You are researching the regulation of cell-size control and discover that a signaling pathway that acts through a particular enzyme-coupled receptor is important for the size growth (enlargement) of rat kidney cells. Receptor activation causes activation of adenylyl cyclase, which ultimately leads to the activation of PKA. PKA then phosphorylates a transcription factor called BTS on threonine 84. This phosphorylation is required to allow BTS to bind to specific regulatory DNA sequences, increasing the transcription of Zrt2, a gene encoding a protein vital for kidney cell growth.
You find that kidney cells without this receptor are 25% smaller than normal cells. When you measure cells expressing a constitutively active version of PKA, you find they are 25% bigger than normal kidney cells. Based on these results, predict whether a kidney cell’s size would be bigger or smaller than normal kidney cells in each of the following circumstances. Explain why in 1-2 sentences for each.
- You add a drug that increases the activity of cyclic AMP phosphodiesterase.
- You mutate the cAMP-binding sites in the regulatory subunits of PKA, so that the complex binds cAMP more tightly.
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