Question

Describe the functions of the complexes that interact with the ribosome near its polypeptide exit channel.

Short answer

The complexes interact with the ribosome near its polypeptide exit channel to ensure the proper folding of the polypeptide and how they will reach their destination. They also perform the posttranslational modification of the proteins.

Step-by-step solution

Ribosome

The ribosome is the structure that interacts with the RNA molecules to read the instructions and produce polypeptide chains with the help of transfer RNA. The polypeptides emerge from the ribosome through an exit channel.

Function of complexes interacting with ribosome

Some complexes interact with the ribosome near its polypeptide exit channel. For example, trigger factors interact with ribosomes to recognize the hydrophobic segments of nascent polypeptides and shield them to prevent the misfolding and aggregation of polypeptides. Chaperones like DnaK and DnaJ interact to protect the longer polypeptides.

Some proteins bind with the ribosome to perform posttranslational modification of proteins. The ribonucleoprotein called signal recognition protein (SRP) interacts with ribosomes near the exit site torecognize the signal sequences present at the terminal of the polypeptide chain.