Steric exclusion and protein conformation determine the localization of plasma membrane transporters

Nat Commun. 2018 Feb 5;9(1):501. doi: 10.1038/s41467-018-02864-2.

Abstract

The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, MCC/eisosomes and MCPs, named after the protein residents Can1 and Pma1, respectively. Using high-resolution fluorescence microscopy techniques we show that Can1 and the homologous transporter Lyp1 are able to diffuse into the MCC/eisosomes, where a limited number of proteins are conditionally trapped at the (outer) edge of the compartment. Upon addition of substrate, the immobilized proteins diffuse away from the MCC/eisosomes, presumably after taking a different conformation in the substrate-bound state. Our data indicate that the mobile fraction of all integral plasma membrane proteins tested shows extremely slow Brownian diffusion through most of the PM. We also show that proteins with large cytoplasmic domains, such as Pma1 and synthetic chimera of Can1 and Lyp1, are excluded from the MCC/eisosomes. We hypothesize that the distinct localization patterns found for these integral membrane proteins in S. cerevisiae arises from a combination of slow lateral diffusion, steric exclusion, and conditional trapping in membrane compartments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport Systems, Basic / chemistry*
  • Amino Acid Transport Systems, Basic / metabolism
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Diffusion
  • Fluorescence Recovery After Photobleaching
  • Kinetics
  • Membrane Microdomains
  • Protein Conformation
  • Protein Transport
  • Proton-Translocating ATPases / chemistry*
  • Proton-Translocating ATPases / metabolism
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / metabolism

Substances

  • Amino Acid Transport Systems, Basic
  • CAN1 protein, S cerevisiae
  • LYP1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • PMA1 protein, S cerevisiae
  • Proton-Translocating ATPases