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

Abstract

Exocyst-positive organelle (EXPO) is a double-membrane organelle mediating unconventional protein secretion in plants. The Arabidopsis exocyst subunit AtExo70E2 is essential for the recruitment of other exocyst subunits to EXPO and plays a key role in EXPO formation in both plant and animal cells.

Cell Wall Maturation of Arabidopsis Trichomes Is Dependent on Exocyst Subunit EXO70H4 and Involves Callose Deposition

“…Formation of other double-membrane bodies has been reported for the EXO70E2 subunit (Wang et al, 2010). Overexpression of EXO70E2 also induces double-membrane structures in animal cells (Ding et al, 2014). This may reflect an exocyst-independent effect of EXO70 on the membrane curvature, which was reported in animal cells (Zhao et al, 2013).…”

Activation of the Rab7 GTPase by the MON1-CCZ1 Complex Is Essential for PVC-to-Vacuole Trafficking and Plant Growth in Arabidopsis

“…Images were processed using Adobe Photoshop as described previously (Jiang and Rogers, 1998;Shen et al, 2013a). Time-lapse movie and images were obtained by spinning disc confocal microscopy (Andor) and analyzed by Imaris software (Bitplane) as described previously (Wang et al, 2010;Ding et al, 2014).…”

EXPO and Autophagosomes are Distinct Organelles in Plants

“…This has led to the suggestion that plants may have multiple exocyst complexes (Cvr cková et al, 2012). Indeed, whereas an Exo70A1-type exocyst is required for conventional secretory processes (Hála et al, 2008;Zárský et al, 2009), an Exo70E2-type exocyst appears to be characteristic for unconventional protein secretion (Wang et al, 2010;Ding et al, 2012Ding et al, , 2014aDing et al, , 2014b. Furthermore, Exo70B1 seems to be specifically needed for the fusion of autophagosomes with the vacuole (Kulich et al, 2013).…”

“…The Exo70E2-positive structures, termed exocystpositive organelles (EXPO), in plants are 500 to 800 nm in diameter and have two boundary membranes (Wang et al, 2010;Ding et al, 2014b). As such, they are morphologically indistinguishable from autophagosomes, both in animals (Yang and Klionsky, 2010) and in plants (Zhuang et al, 2013).…”