Research Article

Border Control—A Membrane-Linked Interactome of Arabidopsis

Science  16 May 2014:
Vol. 344, Issue 6185, pp. 711-716
DOI: 10.1126/science.1251358

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Degrees of Separation

Proteins embedded in membranes represent an interesting point of communication between the cell and its environment, but their localization to membranes can make them difficult to study. Jones et al. (p. 711) found an approach to catalog thousands of interactions involving membrane proteins and membrane-associated signaling machinery—including many previously uncharacterized proteins. With a focus on the model plant Arabidopsis, several of the identified interactions fill gaps in important signal transduction chains, while others point to functions for enigmatic unknown proteins.

Abstract

Cellular membranes act as signaling platforms and control solute transport. Membrane receptors, transporters, and enzymes communicate with intracellular processes through protein-protein interactions. Using a split-ubiquitin yeast two-hybrid screen that covers a test-space of 6.4 × 106 pairs, we identified 12,102 membrane/signaling protein interactions from Arabidopsis. Besides confirmation of expected interactions such as heterotrimeric G protein subunit interactions and aquaporin oligomerization, >99% of the interactions were previously unknown. Interactions were confirmed at a rate of 32% in orthogonal in planta split–green fluorescent protein interaction assays, which was statistically indistinguishable from the confirmation rate for known interactions collected from literature (38%). Regulatory associations in membrane protein trafficking, turnover, and phosphorylation include regulation of potassium channel activity through abscisic acid signaling, transporter activity by a WNK kinase, and a brassinolide receptor kinase by trafficking-related proteins. These examples underscore the utility of the membrane/signaling protein interaction network for gene discovery and hypothesis generation in plants and other organisms.

  • * Present address: College of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035 China.

  • Present address: Department of Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53715, USA.

  • Present address: Five Prime Therapeutics, South San Francisco, CA 94080, USA.

  • § Present Address: Department of Biology, Stanford University, Stanford, CA 94305, USA.

  • Present address: Centre for Organismal Studies, Universität Heidelberg, 69120 Heidelberg, Germany, Cluster of Excellence CellNetworks, 69120 Heidelberg, Germany.

  • Present address: Department of Agronomy, Iowa State University, Ames, IA 50011, USA.

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