Minisymposium 21: Protein and Vesicle Trafficking

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Abs # M2102: Matrix protein targeting to the plant Golgi apparatus

Presenter:	Brandizzi, Federica       Contact Presenter
Authors	Brandizzi, Federica  (B) (A)  Matheson, Loren  (A)   Stefano, Giovanni  (A)
Affiliations:	(A): University Of Saskatchewan (B): Plant Research Laboratory - Michigan State University

The plant Golgi apparatus maintains a cis- to trans-cisternae organization while moving in the cytoplasm. At the same time, vesicles that are tethered to these stacks fuse with the Golgi and transport protein to and from this organelle. To date, the events resulting in protein trafficking and structural maintenance of the plant Golgi apparatus are poorly understood. Golgin proteins are components of a matrix that is involved in vesicle docking as well as linking Golgi cisternae. Arabidopsis has homologues of mammalian and yeast golgins^1,2; however information on the distribution of plant golgins and their molecular effectors is limited. ARF GTPases play a central role in regulating membrane dynamics and protein transport which makes these proteins ideal candidates for a role in golgin recruitment to the plant Golgi apparatus. We have explored membrane traffic organization and Golgi integrity by characterizing peripheral golgins and their effectors. Utilizing live cell imaging and biochemical techniques we have established that ARL1 has a role in binding AtGRIP, a plant golgin, to the Golgi apparatus². In addition, observation of an interaction between a plant homologue of hsGMAP210 and Golgi-localized ARF proteins was observed suggesting a new role for members of the ARF family in the recruitment of plant golgins. Site-directed mutagenesis has demonstrated specific residues on both the ARF and golgin proteins important for the interactions. An appreciation of the differences between systems across kingdoms makes the investigation of the mechanisms that regulate Golgi apparatus architecture and protein transport essential to understanding the secretory pathway in plants. ¹Renna et al. 2005. Plant Mol Biol. 58:109-122. ²Stefano et al. 2006. Plant Mol Biol. in press.