Question

When proteins are synthesized on ER membrane - bound ribosomes, the signal peptide emerging from the ribosome binds to the signal recognition particle (SRP) complex. The SRP complex contains _________.

Answer 1

Proteins synthesized on ER-bound ribosomes involve an SRP binding to the signal peptide of the polypeptide. The SRP-Ribosome complex interacts with the RER membrane to ensure proper synthesis and processing of the proteins. The SRP complex necessary for this process contains RNA and proteins.

Step-by-step explanation:

When proteins are synthesized on ER membrane-bound ribosomes, the signal peptide emerging from the ribosome binds to the signal recognition particle (SRP) complex. The SRP complex contains RNA and proteins.

The steps involved include:

1. An SRP binds to the hydrophobic signal peptide.
2. Elongation stops until the ribosome-SRP complex finds the Rough Endoplasmic Reticulum (RER) membrane.
3. The ribosome-SRP complex binds to an SRP receptor on the RER membrane.
4. SRP detaches from the polypeptide chain, allowing translation elongation to resume through a translocation channel.
5. A signal peptidase in the RER membrane catalyzes hydrolysis of the signal peptide.
6. Elongation continues and the polypeptide begins to fold in the RER.

These steps are essential for the proper synthesis and processing of proteins that are destined for secretion or for incorporation into the cell membrane.