These authors contributed equally to this work.
The Syntaxins SYP31 and SYP81 Control ER–Golgi Trafficking in the Plant Secretory Pathway
Version of Record online: 7 AUG 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Munksgaard
Volume 9, Issue 10, pages 1629–1652, October 2008
How to Cite
Bubeck, J., Scheuring, D., Hummel, E., Langhans, M., Viotti, C., Foresti, O., Denecke, J., Banfield, D. K. and Robinson, D. G. (2008), The Syntaxins SYP31 and SYP81 Control ER–Golgi Trafficking in the Plant Secretory Pathway. Traffic, 9: 1629–1652. doi: 10.1111/j.1600-0854.2008.00803.x
- Issue online: 15 SEP 2008
- Version of Record online: 7 AUG 2008
- Received 9 April 2008, revised and accepted for publication 21 July 2008, uncorrected manuscript published online 7 August 2008, published online 26 August 2008
- BFA resistance;
- SNARE overexpression;
Overexpression of the Golgi and endoplasmic reticulum (ER) syntaxins SYP31 and SYP81 strongly inhibits constitutive secretion. By comparing the secreted reporter α-amylase with the ER-retained reporter α-amylase-HDEL, it was concluded that SYP81 overexpression inhibits both retrograde and anterograde transport, while SYP31 overexpression mainly affected anterograde transport. Of the other interacting SNAREs investigated, only the overexpression of MEMB11 led to an inhibition of protein secretion. Although the position of a fluorescent tag does not influence the correct localization of the fusion protein, only N-terminal-tagged SYP31 retained the ability of the untagged SNARE to inhibit transport. C-terminal-tagged SYP31 failed to exhibit this effect. Overexpression of both wild-type and N-terminal-tagged syntaxins caused standard Golgi marker proteins to redistribute into the ER. Nevertheless, green fluorescent protein (GFP)–SYP31 was still visible as fluorescent punctae, which, unlike SYP31–GFP, were resistant to brefeldin A treatment. Immunogold electron microscopy showed that endogenous SYP81 is not only present at the ER but also in the cis Golgi, indicating that this syntaxin cycles between these two organelles. However, when expressed at non-inhibitory levels, YFP–SYP81 was seen to locate principally to subdomains of the ER. These punctate structures were physically separated from the Golgi, suggesting that they might possibly reflect the position of ER import sites.