Rough ER and protein synthesis

[Pigglyjuff]

---

Members don't see this ad.

When protein synthesis occurs at the ER, is the protein formed inside or outside the ER membrane?

 

[Ace-Co-A]

Ribosomes that "stud" the external face of the rough ER carry out protein synthesis. The protein is then (or is simultaneously) translocated into the lumen of the ER, where it is then prepped for secretion/transmembrane function (via the secretory pathway).

 

[sciencebooks]

Ribosomes that "stud" the external face of the rough ER carry out protein synthesis. The protein is then (or is simultaneously) translocated into the lumen of the ER, where it is then prepped for secretion/transmembrane function (via the secretory pathway).

👍 I've actually been questioned on these details too: A signal peptide binds to the membrane of the RER at the signal recognition peptide and leads the rest of the protein into the ER. Peptidase, inside the ER, cuts off the signal peptide.

 

[Pigglyjuff]

👍 I've actually been questioned on these details too: A signal peptide binds to the membrane of the RER at the signal recognition peptide and leads the rest of the protein into the ER. Peptidase, inside the ER, cuts off the signal peptide.

So it goes AA from cytoplasm into ribosomes --> protein inside the ER?

 

[curt656]

So it goes AA from cytoplasm into ribosomes --> protein inside the ER?

When the ribosome starts translation, a signal sequence is formed at the beginning of the peptide which triggers an SRP (signal recognition peptide) to bind to it. Once it binds, the ribosome stops translation and the SRP drags it to the ER and the SRP attaches to the SRP receptor. Once the SRP/receptor complex is formed, a transposon opens in the membrane allowing the ribosome to resume translation and the peptide crosses the membrane into the ER. As the peptide enters the ER a membrane protein, signal peptidase, cleaves the signal sequence and the peptide begins to fold inside the ER lumen (or the peptide, if it contains stop transfer anchor sequences, can be embedded into the ER membrane).

 

[sciencebooks]

When the ribosome starts transcription, a signal sequence is formed at the beginning of the peptide which triggers an SRP (signal recognition peptide) to bind to it. Once it binds, the ribosome stops transcription and the SRP drags it to the ER and the SRP attaches to the SRP receptor. Once the SRP/receptor complex is formed, a transposon opens in the membrane allowing the ribosome to resume transcription and the peptide crosses the membrane into the ER. As the peptide enters the ER a membrane protein, signal peptidase, cleaves the signal sequence and the peptide begins to fold inside the ER lumen (or the peptide, if it contains stop transfer anchor sequences, can be embedded into the ER membrane).

👍 I think this is a really succinct description and think it's all on with ONE correction: Ribsosomes perform translation

 

[curt656]

👍 I think this is a really succinct description and think it's all on with ONE correction: Ribsosomes perform translation

Uh, lol! I can be such a klutz sometimes. I always transpose the two terms. Can I blame it on posting at 3:30 in the morning???? I will edit.

 

[sciencebooks]

Uh, lol! I can be such a klutz sometimes. I always transpose the two terms. Can I blame it on posting at 3:30 in the morning???? I will edit.

Haha, it happens to the best of us. The worst is when you're going over a full length you did and realize you had a ridiculous moment, 😳.

 

[curt656]

At least it shows I wasn't copying out of a book, lol!

 

[sciencebooks]

At least it shows I wasn't copying out of a book, lol!

Man, I don't know, I've seen quite a bit of misprints in some EK material lately... 😛