Endocytosis optimizes the dynamic localization of membrane proteins that regulate cortical polarity.
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.
Marco
Eugenio
E
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Wedlich-Soldner
Roland
R
Li
Rong
R
Altschuler
Steven J
SJ
Wu
Lani F
LF
D001692:Biological Transport; D016764:Cell Polarity; D004058:Diffusion; D004705:Endocytosis; D025461:Feedback, Physiological; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D008954:Models, Biological; D038761:Photobleaching; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / Q000378:metabolism*
D008565:Membrane Proteins; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae