You have isolated a primary signaling factor from the blood of a space alien, wh

Question

You have isolated a primary signaling factor from the blood of a space alien, which you name XFF (for X-files factor). You also have isolated various types of alien cells which appear to interact with XFF. Based on preliminary data, you think that XFF could be similar to one of three compounds normally found in human blood: epidermal growth factor (EGF), epinephrine, or estrogen.

A) You add a large amount of XFF to cultured alien liver cells and notice glycogen breakdown. What type of signaling factor does this indicate XFF is? Explain / justify your answer.

B) What type of receptor / signaling pathway would you study to demonstrate XFF is most like EGF? Explain / justify your answer.

C) You are still not sure what type of signaling factor XFF is, so you need to test the estrogen hypothesis.  You decide to investigate other XFF properties using fluorescently labeled XFF. You add the labeled XFF to a dish of alien cells.  If XFF acts like estrogen, where do you expect to find this molecule? Explain / justify your answer.

Explanation / Answer

A- Given that upon binding to its receptor XEF leads to the breakdown of Glycogen. In case of mammalian muscles and liver cells, upon binding to its receptor epinephrine leads to activation of the cascade which leads to activation of the enzyme which is responsible for the breakdown of glycogen into glucose. So, in this case, XFF indicate epinephrine pathway.

B- EGF signalling is the member receptor tyrosine kinase family (RTK) of proteins. EGF signalling leads to activation of various pathways such as RAs/Raf signalling, Phosphatidylinositol 3-kinase/Akt signalling cascade, Signal transducers and activators of transcription (STAT) pathway. So if upon binding of XFF to its receptor any of the above-mentioned pathways is activated then we can say that XFF is most like EGF

C -Estrogen is a steroid hormone which can easily cross the plasma membrane. Inside the cytoplasm, it binds to its receptor called as estrogen receptor. Once it is bound to its receptor, estrogen moves towards the nucleus and binds to Estrogen responsive element.

So if XFF behaves like estrogen then we should observe the fluorescence in the nucleus.  

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