protein localization to cell surface

Definition

Target type: biologicalprocess

A process in which a protein is transported to, or maintained in, a location within the external part of the cell wall and/or plasma membrane. [GOC:mah]

Protein localization to the cell surface is a complex process that ensures proteins are delivered to their correct destinations within the cell. It is crucial for cellular function and communication, as it allows cells to respond to their environment and interact with other cells. Here's a detailed breakdown of the process:

1. **Synthesis and Folding:** Proteins destined for the cell surface are synthesized on ribosomes bound to the endoplasmic reticulum (ER). As the protein is being synthesized, it enters the ER lumen, a space within the ER. Here, it undergoes folding and modification, ensuring it acquires its correct three-dimensional structure.

2. **ER Quality Control:** Once inside the ER, proteins are subjected to rigorous quality control mechanisms. Chaperone proteins assist in proper folding, and misfolded or improperly assembled proteins are targeted for degradation. This ensures that only correctly folded and functional proteins proceed to the cell surface.

3. **Glycosylation:** Many proteins destined for the cell surface undergo glycosylation, the addition of sugar chains (glycans). Glycosylation plays a crucial role in protein folding, stability, and recognition by other molecules.

4. **Transport through the Golgi Apparatus:** After the ER, proteins move to the Golgi apparatus, a series of stacked membrane-bound sacs. Here, they undergo further modification and sorting. The Golgi apparatus acts like a processing plant, adding more sugars, lipids, or other modifications to proteins before they are packaged into vesicles.

5. **Vesicle Formation and Trafficking:** From the Golgi apparatus, proteins are packaged into small membrane-bound vesicles. These vesicles bud off from the Golgi and transport their cargo to the cell surface. This process involves specific protein coat complexes that aid in vesicle formation and targeting.

6. **Exocytosis:** At the plasma membrane, the vesicle fuses with the cell membrane, releasing its contents outside the cell. This process is called exocytosis and is a key mechanism for delivering proteins to the cell surface.

7. **Targeting Signals:** Proteins destined for the cell surface often contain specific amino acid sequences known as signal peptides or targeting signals. These signals guide the protein through the ER, Golgi, and to the correct location on the cell surface.

8. **Regulation:** The localization of proteins to the cell surface is tightly regulated. The cell can control the rate of protein synthesis, folding, and trafficking to adjust its response to external stimuli.

9. **Specialized Pathways:** Some proteins have specialized pathways for reaching the cell surface. For example, proteins destined for specific membrane domains, such as tight junctions or adherens junctions, require additional sorting and targeting signals.

In summary, protein localization to the cell surface is a multi-step process that ensures the proper delivery of functional proteins to their designated locations. It involves protein synthesis, folding, quality control, glycosylation, transport through the Golgi, vesicle formation, exocytosis, and specific targeting signals.'
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Proteins (2)

Compounds (7)