Temporal Ordering in Endocytic Clathrin-Coated Vesicle Formation via AP2 Phosphorylation

Area of Science:

• Cell Biology
• Molecular Biology

Background:

• Clathrin-mediated endocytosis (CME) is essential for cellular protein homeostasis.
• The AP2 complex is the main endocytic adaptor during mammalian CME.

Purpose of the Study:

• To investigate the role of micro2 subunit phosphorylation in CME.
• To elucidate the structural and functional consequences of micro2Thr156 phosphorylation.

Main Methods:

• Analysis of phosphorylation dynamics during clathrin-coated pit (CCP) formation.
• Structural studies of AP2 and NECAP interactions.
• Functional assays assessing CCP maturation and CME rates.

Main Results:

• micro2Thr156 phosphorylation increases during CCP lifetime, favoring a cargo-bound AP2 conformation.
• Phosphorylation creates a binding site for NECAP proteins, which recruit SNX9.
• Structural basis for AP2-NECAP interaction and NECAP-SNX9 recruitment elucidated.

Conclusions:

• Phosphorylation of AP2's micro2 subunit is a key temporal regulator of CME.
• This regulatory system ensures efficient CCP maturation and protein internalization.
• Disruption impairs CME rates by stalling CCP progression.