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How are proteins released from a cell?

Published in Protein Secretion 2 mins read

Proteins destined for secretion are released from a cell through a regulated process involving transport vesicles and the plasma membrane.

Protein Secretion Pathway

Here's a breakdown of the protein secretion pathway, based on the provided reference:

  1. Sorting in the Trans-Golgi Network (TGN): Proteins synthesized for secretion are sorted in the TGN. This sorting determines which pathway they will take for release.

  2. Vesicle Formation: Two types of vesicles are involved:

    • Constitutive Secretory Pathway (CSP): Proteins are sorted into vesicles that are nonclathrin-coated.
    • Regulated Secretory Pathway (RSP): Proteins are sorted into vesicles that are clathrin-coated.
  3. Vesicle Trafficking: The secretory vesicles then move towards the plasma membrane.

  4. Release at the Plasma Membrane: Finally, the vesicles fuse with the plasma membrane, releasing their protein content in a regulated manner. This release is triggered by specific signals depending on the cell type and the protein being secreted.

Table Summarizing Protein Secretion

Step Description Vesicle Type Coating Protein
Sorting in TGN Proteins destined for secretion are sorted into different pathways based on their final destination and regulatory requirements. CSP (Constitutive), RSP (Regulated) N/A
Vesicle Formation Proteins are packaged into secretory vesicles. CSP, RSP Nonclathrin, Clathrin respectively
Vesicle Trafficking Vesicles move towards the plasma membrane. CSP, RSP N/A
Release at Plasma Membrane Vesicles fuse with the plasma membrane, releasing their protein cargo. This process is regulated, especially in the RSP, and often triggered by specific signals. CSP, RSP N/A