Exo70E2 is essential for exocyst subunit recruitment and EXPO formation in both plants and animals

• DOI: 10.1091/mbc.e13-10-0586
• Publication Date: 2013-12-05T01:38:49Z
• Authors: Yu Ding; Juan Wang; John Ho Chun Lai; Vivian Hoi Ling Chan; Xiangfeng Wang; Yi Cai; Xiaoyun Tan; Yiqun Bao; Jun Xia; David G. Robinson; Liwen Jiang
• Keywords: Exocyst; Bimolecular fluorescence complementation; Organelle

In contrast to a single copy of Exo70 in yeast and mammals, the Arabidopsis genome contains 23 paralogues (AtExo70). Using AtExo70E2 its GFP fusion as probes, we recently identified novel double-membrane organelle termed exocyst-positive (EXPO) that mediates an unconventional protein secretion plant cells. Here further demonstrate is essential for exocyst subunit recruitment EXPO formation both plants animals. By performing transient expression protoplasts, established number subunits (especially members Sec family) are unable be recruited absence AtExo70E2. The paralogue AtExo70A1 substitute this regard. Fluorescence resonance energy transfer assay bimolecular fluorescence complementation analyses confirm interaction between Sec6 Sec10. AtExo70E2, but not counterpart, also capable inducing animal cell line (HEK293A cells). Electron microscopy confirms presence double-membraned, EXPO-like structures HEK293A cells expressing Inversely, neither human nor homologues cause protoplasts. These results point specific crucial role formation.