eukaryotic mRNA production

[chokiepie]

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In eukaryotic mRNA production,
does addition of a 7 methyl guanosine cap to the 5' end of pre-mRNA occurs in cytosol or nucleus?
Kaplan LN mentions Nucleus and UWorld Q 2035, mentions cytosol?

Would someone please shed some light on this?

 

[Step1Hash]

In eukaryotic mRNA production,
does addition of a 7 methyl guanosine cap to the 5' end of pre-mRNA occurs in cytosol or nucleus?
Kaplan LN mentions Nucleus and UWorld Q 2035, mentions cytosol?

Would someone please shed some light on this?

The addition of the 5' cap happens in two steps. The first is adding the guanosine to the 5' end in the nucleus and the 2nd is methylating the 5'-guanosine at the 7 position to make the 7-methyguanosine. Both steps iv'e seen termed "5' cap." But if it says 7-methylguanosine then its in the cytosol and if it says 5' guanosine cap then its in the nucleus.

I assume Kaplan just said "5' cap"? if not, then I might be wrong in how I understood the concept.

hope this helps

 

[Sheldor]

The addition of the 5' cap happens in two steps. The first is adding the guanosine to the 5' end in the nucleus and the 2nd is methylating the 5'-guanosine at the 7 position to make the 7-methyguanosine. Both steps iv'e seen termed "5' cap." But if it says 7-methylguanosine then its in the cytosol and if it says 5' guanosine cap then its in the nucleus.

I assume Kaplan just said "5' cap"? if not, then I might be wrong in how I understood the concept.

hope this helps

This is how Uworld explained it, and what I took to be true since I haven't seen anything to contradict it.

 

[MossPoh]

Yup, I've been pimped on that question in some form about 3 times now. Divided into two parts. The initial 5'cap is in the nucleus and is kind of its get out of jail free card. Finishing touches are done out in the cytosol where it really tightens up its act.

 

[Sheldor]

Yup, I've been pimped on that question in some form about 3 times now. Divided into two parts. The initial 5'cap is in the nucleus and is kind of its get out of jail free card. Finishing touches are done out in the cytosol where it really tightens up its act.

Obviously a vital fact to our future medical practice. Sheesh, the things they think are important...

 

[uvajrl]

The addition of the 5' cap happens in two steps. The first is adding the guanosine to the 5' end in the nucleus and the 2nd is methylating the 5'-guanosine at the 7 position to make the 7-methyguanosine. Both steps iv'e seen termed "5' cap." But if it says 7-methylguanosine then its in the cytosol and if it says 5' guanosine cap then its in the nucleus.

I assume Kaplan just said "5' cap"? if not, then I might be wrong in how I understood the concept.

hope this helps

For those of you who have noticed this recently on UW Q#2035, I wanted to update the consensus on this thread as its one of the first searches to show up on search engines. Updated First Aid errata says to delete the phrase on page 75 regarding the 7-methylguanosine addition in the cytosol. Thus, UW is correct. All steps involving the 5' cap (including this process) occur in the nucleus.

 

[futuredoctor10]

For those of you who have noticed this recently on UW Q#2035, I wanted to update the consensus on this thread as its one of the first searches to show up on search engines. Updated First Aid errata says to delete the phrase on page 75 regarding the 7-methylguanosine addition in the cytosol. Thus, UW is correct. All steps involving the 5' cap (including this process) occur in the nucleus.

WOW glad you posted this. Missed this question in UW, because I read "7-methylguanosine in the cytosol" in FA. Then I came up with this huge explanation of how it might all work!!! Need to check out this new updated Errata

 

[Phloston]

Obviously a vital fact to our future medical practice. Sheesh, the things they think are important...

Haha, yeah..

For those of you who have noticed this recently on UW Q#2035, I wanted to update the consensus on this thread as its one of the first searches to show up on search engines. Updated First Aid errata says to delete the phrase on page 75 regarding the 7-methylguanosine addition in the cytosol. Thus, UW is correct. All steps involving the 5' cap (including this process) occur in the nucleus.

Dude, WTF!! When I saw the OP's question, I thought "cytosol," and was glad that I remembered that from FA. It's always fun to un-learn stuff too.

 

[batch5000]

For those of you who have noticed this recently on UW Q#2035, I wanted to update the consensus on this thread as its one of the first searches to show up on search engines. Updated First Aid errata says to delete the phrase on page 75 regarding the 7-methylguanosine addition in the cytosol. Thus, UW is correct. All steps involving the 5' cap (including this process) occur in the nucleus.

So what are the P proteins that bind in the cytosol for?

 

[uvajrl]

So what are the P proteins that bind in the cytosol for?

Regulation of translation by degrading the mRNA after it leaves the nucleus... Wasting the cell's time and resources like FA wastes our time and money with this riddled-with-errors book and its multiple versions of errata that switch back and forth

 

[batch5000]

Regulation of translation by degrading the mRNA after it leaves the nucleus... Wasting the cell's time and resources like FA wastes our time and money with this riddled-with-errors book and its multiple versions of errata that switch back and forth

Haha. Thanks, I think I get it. Sounds like it might be pretty low-yield. I think its probably most important to know that that part is in the cytosol.

 

[futuredoctor10]

The addition of the 5' cap happens in two steps. The first is adding the guanosine to the 5' end in the nucleus and the 2nd is methylating the 5'-guanosine at the 7 position to make the 7-methyguanosine. Both steps iv'e seen termed "5' cap." But if it says 7-methylguanosine then its in the cytosol and if it says 5' guanosine cap then its in the nucleus.

So I am assuming that with the new FA errata, the above statements should actually say that all of it - 5' guanosine cap, 7-methylguanosine - are processing steps that occur in the nucleus... right??

 

[Aclamity]

So I am assuming that with the new FA errata, the above statements should actually say that all of it - 5' guanosine cap, 7-methylguanosine - are processing steps that occur in the nucleus... right??

my god I hope so. Would be evil of the NBME to put this question on the test to screw over all the people who blindly trusted FA.