Function of signal recognition particle (SRP) is

Options

A. Binding to signal protein
B. Reach the SRP receptor on ER membrane
C. Move the ribosome producing secretory protein over the ER membrane.
D. All the above.

Answer

To answer the question regarding the function of the signal recognition particle (SRP), we can break down the information into clear steps:

### Step-by-Step Solution:

1. **Understanding SRP**: The signal recognition particle (SRP) is a ribonucleoprotein complex that plays a crucial role in the targeting of proteins to the endoplasmic reticulum (ER) in eukaryotic cells.

2. **Function of SRP**: The primary function of SRP is to recognize and bind to the signal peptide of nascent proteins. These signal peptides are short sequences of amino acids that direct the protein to the ER.

3. **Binding to Signal Protein**: The first function of SRP is to bind to the signal protein (signal peptide). This is essential for the targeting of the protein to the ER membrane.

4. **Reaching the SRP Receptor**: After binding to the signal peptide, the SRP then facilitates the transport of the ribosome-mRNA-polypeptide complex to the SRP receptor located on the ER membrane. This is the second function of SRP.

5. **Moving Ribosomes**: The third function of SRP is to assist in moving the ribosome that is producing the secretory protein to the ER membrane. This ensures that the protein is translocated into the ER for further processing.

6. **Conclusion**: Since SRP performs all the above functions—binding to the signal protein, reaching the SRP receptor on the ER membrane, and moving the ribosomes producing secretory proteins over the ER membrane—the correct answer is "all the above."

### Final Answer:
The function of the signal recognition particle (SRP) is **all the above**.

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