Final answer:
The function of the Signal Recognition Particle (SRP) is to recognize and bind to the signal peptide of a nascent secretory protein, halting synthesis until the complex can attach to the rough endoplasmic reticulum (RER). After docking to an SRP receptor, translation resumes and the protein is co-translationally translocated into the RER where the signal peptide is removed.
Step-by-step explanation:
The Signal Recognition Particle (SRP) is essential for directing newly synthesized proteins to the correct location within a cell, usually the rough endoplasmic reticulum (RER). When a protein destined for secretion starts to emerge from the ribosome, the SRP binds to the hydrophobic signal peptide at the amino terminus of the nascent polypeptide. This binding halts protein synthesis temporarily.
Next, the SRP-ribosome complex is targeted to the RER membrane, where it binds to an SRP receptor. Upon docking, the SRP detaches, allowing for protein synthesis to resume. The elongating polypeptide passes into the interior of the RER, where a signal peptidase catalyzes the cleavage of the signal peptide, allowing the rest of the protein to be properly processed within the RER.
In summary, the SRP has a vital role in ensuring that proteins are correctly targeted and integrated into the RER membrane, a process crucial for the production of secretory and membrane proteins.