Journal
BIOPHYSICAL JOURNAL
Volume 108, Issue 7, Pages 1633-1644Publisher
CELL PRESS
DOI: 10.1016/j.bpj.2015.02.011
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Funding
- Agencia Nacional de Investigacion e Innovacion de Uruguay [FCE-3-2011-1-5942]
- Programa de Desarrollo de Ciencias Basicas
- MERCOSUR Structural Convergence Fund (Fondo para la Convergencia Estructural del MERCOSUR, FOCEM) [COF 03/11]
- National Institutes of Health [NIH P41-GM103540, NIH P50-GM076516]
- Journal of Cell Science Traveling Fellowship
- Wood/Whelan Fellowship from the International Union of Biochemistry and Molecular Biology
- Sistema Nacional de Becas
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Eisosomes are plasma membrane domains concentrating lipids, transporters, and signaling molecules. In the budding yeast Saccharomyces cerevisiae, these domains are structured by scaffolds composed mainly by two cytoplasmic proteins Pil1 and Lsp1. Eisosomes are immobile domains, have relatively uniform size, and encompass thousands of units of the core proteins Pil1 and Lsp1. In this work we used fluorescence fluctuation analytical methods to determine the dynamics of eisosome core proteins at different subcellular locations. Using a combination of scanning techniques with autocorrelation analysis, we show that Pil1 and Lsp1 cytoplasmic pools freely diffuse whereas an eisosome-associated fraction of these proteins exhibits slow dynamics that fit with a binding-unbinding equilibrium. Number and brightness analysis shows that the eisosome-associated fraction is oligomeric, while cytoplasmic pools have lower aggregation states. Fluorescence lifetime imaging results indicate that Pil1 and Lsp1 directly interact in the cytoplasm and within the eisosomes. These results support a model where Pil1-Lsp1 heterodimers are the minimal eisosomes building blocks. Moreover, individual-eisosome fluorescence fluctuation analysis shows that eisosomes in the same cell are not equal domains: while roughly half of them are mostly static, the other half is actively exchanging core protein subunits.
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