Shape transitions during clathrin-induced endocytosis.

Area of Science:

• Cell biology
• Biophysics

Background:

• Endocytosis is a fundamental cellular process for macromolecule uptake.
• Clathrin-mediated endocytosis (CME) utilizes clathrin protein to form coated membrane buds for cargo internalization.
• The dynamic evolution of clathrin coat morphology and energetics during CME are not fully understood.

Purpose of the Study:

• To analyze experimental data on clathrin coat area and curvature dynamics during CME.
• To challenge existing models of coated membrane bud formation based on new experimental findings.
• To propose a kinetic model for clathrin coat area distribution and explore geometric aspects of bud shape evolution.

Main Methods:

• Analysis of experimental data on clathrin coat morphology and turnover.
• Development of a kinetic model for clathrin coat area distribution.
• Application of geometric considerations to understand coated membrane bud shape evolution.

Main Results:

• Experimental observations of fixed clathrin coat area with increasing curvature and rapid molecular turnover challenge current CME models.
• Analysis reveals features consistent with the clathrin coat's lattice structure.
• A proposed kinetic model explains observed clathrin coat area distributions.
• Geometric analysis provides insights into the shape evolution of coated membrane buds.

Conclusions:

• The fixed area and rapid turnover of clathrin coats during CME present challenges to existing formation models.
• Membrane curvature may inhibit clathrin deposition, as suggested by a new kinetic model.
• While geometric aspects are partly explained, the energetics of clathrin coat formation remain a significant open question.