Intrinsically Disordered Linker and Plasma Membrane‐Binding Motif Sort Ist2 and Ssy1 to Junctions |
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Authors: | Annemarie Kralt Marco Carretta Muriel Mari Fulvio Reggiori Anton Steen Bert Poolman Liesbeth M. Veenhoff |
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Affiliation: | 1. European Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre, Groningen, The Netherlands;2. Current address: Department of Hematology, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands;3. Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands;4. Department of Biochemistry, University of Groningen, Groningen, The Netherlands |
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Abstract: | Membrane junctions or contact sites are close associations of lipid bilayers of heterologous organelles. Ist2 is an endoplasmic reticulum (ER)‐resident transmembrane protein that mediates associations between the plasma membrane (PM) and the cortical ER (cER) in baker's yeast. We asked the question what structure in Ist2 bridges the up to 30 nm distance between the PM and the cER and we noted that the region spacing the transmembrane domain from the cortical sorting signal interacting with the PM is predicted to be intrinsically disordered (ID). In Ssy1, a protein that was not previously described to reside at membrane junctions, we recognized a domain organization similar to that in Ist2. We found that the localization of both Ist2 and Ssy1 at the cell periphery depends on the presence of a PM‐binding domain, an ID linker region of sufficient length and a transmembrane domain that most probably resides in the ER. We show for the first time that an ID amino acid domain bridges adjacent heterologous membranes. The length and flexibility of ID domains make them uniquely eligible for spanning large distances, and we suggest that this domain structure occurs more frequently in proteins that mediate the formation of membrane contact sites. ![image](https://wol-prod-cdn.literatumonline.com/cms/attachment/6e2063ed-75c4-4d36-877c-f658792906c1/tra12243-gra-0001.png) |
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Keywords: | amino acid signaling endoplasmic reticulum intrinsic disorder membrane junction membrane protein trafficking plasma membrane |
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