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BIO NMDCAT Cytoplasmic Organelles
nmdcat.online July 4, 2026

53. The precise mechanical mechanism by which COPI-coated vesicles selectively capture escaped ER-resident proteins within the Golgi stack relies on the

A. pH gradient altering the affinity of KDEL receptors for their cargo
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B. Direct phosphorylation of cargo molecules by Golgi kinases
C. Electrical potential across the cis-Golgi membrane
D. Binding of clathrin heavy chains to the vesicle core

📝 Explanation

The Golgi has a slightly lower pH than the ER. This acidic environment increases the affinity of KDEL receptors for ER proteins, facilitating their capture into retrograde COPI vesicles.

📖 Additional Information

  • pH gradient altering the affinity of KDEL receptors for their cargo
  • Direct phosphorylation of cargo molecules by Golgi kinases
  • Electrical potential across the cis-Golgi membrane
  • Binding of clathrin heavy chains to the vesicle core

The Golgi has a slightly lower pH than the ER. This acidic environment increases the affinity of KDEL receptors for ER proteins, facilitating their capture into retrograde COPI vesicles.

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