The Potato Sucrose Transporter StSUT1 Interacts with a DRM-Associated Protein Disulfide Isomerase  

作　　者：Undine Krugel Hong-Xia He Konstanze Gier Jana Reins Izabela Chincinska Bernhard Grimm Waltraud X. Schulze Christina Kuhn 

机构地区：[1]Institute of Biology, Department of Plant Physiology, Humboldt University, 10115 Berlin, Germany [2]Max Planck Institute of Molecular Plant Physiology, Am MGhlenberg 1, 14476 Potsdam-Golm, Germany

出　　处：《Molecular Plant》2012年第1期43-62,共20页分子植物（英文版）

摘　　要：Organization of proteins into complexes is crucial for many cellular functions. Recently, the SUT1 protein was shown to form homodimeric complexes, to be associated with lipid raft-like microdomains in yeast as well as in plants and to undergo endocytosis in response to brefeldin A. We therefore aimed to identify SUTl-interacting proteins that might be involved in dimerization, endocytosis, or targeting of SUT1 to raft-like microdomains. Therefore, we identified potato membrane proteins, which are associated with the detergent-resistant membrane （DRM） fraction. Among the proteins identified, we clearly confirmed StSUT1 as part of DRM in potato source leaves. We used the yeast two-hybrid split ubiq- uitin system （SUS） to systematically screen for interaction between the sucrose transporter StSUT1 and other membrane- associated or soluble proteins in vivo. The SUS screen was followed by immunoprecipitation using affinity-purified StSUTl-specific peptide antibodies and mass spectrometric analysis of co-precipitated proteins. A large overlap was ob- served between the StSUTl-interacting proteins identified in the co-immunoprecipitation and the detergent-resistant membrane fraction. One of the SUTl-interacting proteins, a protein disulfide isomerase （PDI）, interacts also with other sucrose transporter proteins. A potential role of the PDI as escort protein is discussed.Organization of proteins into complexes is crucial for many cellular functions. Recently, the SUT1 protein was shown to form homodimeric complexes, to be associated with lipid raft-like microdomains in yeast as well as in plants and to undergo endocytosis in response to brefeldin A. We therefore aimed to identify SUTl-interacting proteins that might be involved in dimerization, endocytosis, or targeting of SUT1 to raft-like microdomains. Therefore, we identified potato membrane proteins, which are associated with the detergent-resistant membrane （DRM） fraction. Among the proteins identified, we clearly confirmed StSUT1 as part of DRM in potato source leaves. We used the yeast two-hybrid split ubiq- uitin system （SUS） to systematically screen for interaction between the sucrose transporter StSUT1 and other membrane- associated or soluble proteins in vivo. The SUS screen was followed by immunoprecipitation using affinity-purified StSUTl-specific peptide antibodies and mass spectrometric analysis of co-precipitated proteins. A large overlap was ob- served between the StSUTl-interacting proteins identified in the co-immunoprecipitation and the detergent-resistant membrane fraction. One of the SUTl-interacting proteins, a protein disulfide isomerase （PDI）, interacts also with other sucrose transporter proteins. A potential role of the PDI as escort protein is discussed.

关 键 词：Protein-protein interactions phloem proteins vesicle trafficking endocytosis. 

分 类 号：Q784[生物学—分子生物学] S511[农业科学—作物学]