peptide secretion

Definition

Target type: biologicalprocess

The controlled release of a peptide from a cell or a tissue. [GOC:add]

Peptide secretion is a complex biological process that involves the movement of newly synthesized peptides from their site of synthesis within the cell to the extracellular space. This process is essential for a wide range of cellular functions, including signaling, communication, and defense. Here is a detailed description of the major steps involved in peptide secretion:

1. **Synthesis and Folding:** Peptide synthesis begins in the ribosomes, where the genetic code is translated into a linear chain of amino acids. As the peptide chain emerges from the ribosome, it starts to fold into its unique three-dimensional structure, guided by interactions between amino acids. This folding process is crucial for the peptide's function and stability.

2. **Translocation to the ER:** Most secreted peptides are synthesized on ribosomes that are associated with the endoplasmic reticulum (ER), a network of interconnected membranes that extends throughout the cytoplasm. As the peptide is being synthesized, it is simultaneously translocated into the lumen of the ER, the space enclosed by the ER membrane. This translocation is facilitated by a protein complex called the translocon.

3. **Protein Folding and Modification:** Within the ER lumen, newly synthesized peptides undergo further folding and modification. These modifications include disulfide bond formation, glycosylation, and the addition of other post-translational modifications. These modifications are essential for the peptide's proper folding, stability, and function.

4. **Quality Control:** The ER also serves as a quality control checkpoint for secreted peptides. If a peptide fails to fold correctly or is otherwise misfolded, it is recognized by chaperone proteins and targeted for degradation. This ensures that only properly folded and functional peptides are secreted from the cell.

5. **Transport to the Golgi:** After folding and modification, the peptides are transported from the ER to the Golgi apparatus, another organelle in the cell. The Golgi apparatus is a series of flattened membrane-bound sacs called cisternae. As peptides move through the Golgi, they undergo further modification and sorting.

6. **Packaging into Vesicles:** In the Golgi, secreted peptides are packaged into transport vesicles, small membrane-bound spheres that bud off from the Golgi. These vesicles contain various enzymes and proteins that are necessary for the final stages of peptide secretion.

7. **Exocytosis:** The transport vesicles then move to the cell surface, where they fuse with the plasma membrane and release their contents into the extracellular space. This process, known as exocytosis, is the final step in peptide secretion.

8. **Targeting and Delivery:** Once released into the extracellular space, secreted peptides can travel to their target cells or tissues. Some peptides act as signaling molecules, binding to receptors on the surface of target cells to elicit specific responses. Others act as structural components, contributing to the formation of extracellular matrices or other structures.

The process of peptide secretion is highly regulated, ensuring that only properly folded and functional peptides are released from the cell. This regulation is crucial for maintaining cellular homeostasis and normal physiological function.'
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Proteins (1)

Compounds (68)