EK 1001 post transnational modfication

[Pediateix]

can someone explain post translational mdoficiation . i am looking at question 908 from the EK 10001 book. does post transitional modification involve the ER?

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[Spectar]

can someone explain post translational mdoficiation . i am looking at question 908 from the EK 10001 book. does post transitional modification involve the ER?

I don't know the specific question you are looking at but I can try and explain post translational modification.
Essentially,post translational modification would involve modifications of proteins already made. There are many modifications that can occur (carboxylation, glycosylation etc.). To my understanding, they usually occur in the Golgi apparatus while being transported out. These modifications can also occur within the cytoplasm (chaperone proteins are sometimes considered post translational modifiers even though they don't add anything, they help with folding).

 

[Pediateix]

I don't know the specific question you are looking at but I can try and explain post translational modification.
Essentially,post translational modification would involve modifications of proteins already made. There are many modifications that can occur (carboxylation, glycosylation etc.). To my understanding, they usually occur in the Golgi apparatus while being transported out. These modifications can also occur within the cytoplasm (chaperone proteins are sometimes considered post translational modifiers even though they don't add anything, they help with folding).

does post involve the ER?

 

[Pediateix]

this is the relevant passage info

the trouble actually begins at the genetic level, with a mutant CFTR gene that codes for a CFTR glycoprotein that is synthesized but fails to mature and cannot proceed beyond th ER.

this is the question

it can be inferred from the passage that the abnormal cftr gene and glycoprotein undergo all of the following process except
a-transcription
b-transaltion
c-pos translational modification
d-replication

 

[desperadoflakes]

So it says that the "glycoprotein is synthesized" which tells you that it's already been transcribed and translated, so the only viable option is post-translational modifications.

Post-translational modification is any modification that happens to the protein that is not a part of normal protein translation or folding. Most modifications, like methylations, acetylations, glycosylations, ubiquitanations occur in the rough ER and the golgi body. To enter the rough ER a protein must contain a signal peptide, usually at the N-terminus. So the mRNA begins to get transcribed in the cytosol, and while it is getting translated another protein called a signal recognition particle (SRP) comes and binds to that signal peptide. When the SRP binds to the signal peptide translation halts and the entire complex goes over to the RER membrane, where the ribosome docks and the rest of the protein is translated into the lumen of the ER. At this point, other stuff can happen depending on the ultimate fate of the protein.

If it's can't proceed beyond the ER that means it probably is missing the correct localization signal to do what it needs to do, and so it can't go to the golgi and get modified further.

 

[Pediateix]

So it says that the "glycoprotein is synthesized" which tells you that it's already been transcribed and translated, so the only viable option is post-translational modifications.

Post-translational modification is any modification that happens to the protein that is not a part of normal protein translation or folding. Most modifications, like methylations, acetylations, glycosylations, ubiquitanations occur in the rough ER and the golgi body. To enter the rough ER a protein must contain a signal peptide, usually at the N-terminus. So the mRNA begins to get transcribed in the cytosol, and while it is getting translated another protein called a signal recognition particle (SRP) comes and binds to that signal peptide. When the SRP binds to the signal peptide translation halts and the entire complex goes over to the RER membrane, where the ribosome docks and the rest of the protein is translated into the lumen of the ER. At this point, other stuff can happen depending on the ultimate fate of the protein.

If it's can't proceed beyond the ER that means it probably is missing the correct localization signal to do what it needs to do, and so it can't go to the golgi and get modified further.

thank you! but you mean So the mRNA begins to get TRANSALTED in the cytoso

 

[desperadoflakes]

Yes watch a video on the signal recognition peptide and it'll all make a lot of sense