Endocytosis optimizes the dynamic localization of membrane proteins that regulate cortical polarity

Cell. 2007 Apr 20;129(2):411-22. doi: 10.1016/j.cell.2007.02.043.


Diverse cell types require the ability to maintain dynamically polarized membrane-protein distributions through balancing transport and diffusion. However, design principles underlying dynamically maintained cortical polarity are not well understood. Here we constructed a mathematical model for characterizing the morphology of dynamically polarized protein distributions. We developed analytical approaches for measuring all model parameters from single-cell experiments. We applied our methods to a well-characterized system for studying polarized membrane proteins: budding yeast cells expressing activated Cdc42. We found that a balance of diffusion, directed transport, and endocytosis was sufficient for accurately describing polarization morphologies. Surprisingly, the model predicts that polarized regions are defined with a precision that is nearly optimal for measured endocytosis rates and that polarity can be dynamically stabilized through positive feedback with directed transport. Our approach provides a step toward understanding how biological systems shape spatially precise, unambiguous cortical polarity domains using dynamic processes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Cell Polarity*
  • Diffusion
  • Endocytosis*
  • Feedback, Physiological
  • Membrane Proteins / analysis
  • Membrane Proteins / metabolism*
  • Models, Biological
  • Photobleaching
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / metabolism*
  • cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / metabolism*


  • Membrane Proteins
  • cdc42 GTP-Binding Protein, Saccharomyces cerevisiae