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.
Highlights
The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, membrane compartment occupied by Can1 (MCC)/eisosomes and membrane compartment occupied by Pma1 (MCP), named after the protein residents Can[1] and Pma[1], respectively
Its PM does contain discrete domains such as the membrane compartment occupied by Can[1] (MCC) and the membrane compartment occupied by Pma[1] (MCP)[4]
We used dualcolor super-resolution microscopy to study the localization of two MCC/eisosome-resident proteins, the integral membrane protein Sur[7] and the scaffolding protein Pil[1]
Summary
The plasma membrane (PM) of Saccharomyces cerevisiae contains membrane compartments, MCC/eisosomes and MCPs, named after the protein residents Can[1] and Pma[1], respectively. The PM has been shown to partition into small compartments, where proteins and lipids diffuse relatively quickly at short-distance scales, but in which long-range mobility is hindered by the membrane skeleton[2,3]. In this model, the hopping of molecules between compartments is a determining factor for the overall lateral motion. Our high-resolution microscopy analysis of the location and diffusion of a range of membrane proteins provides a new perspective on the structure and dynamics of the MCC/ eisosome and the PM of yeast
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