The secretory pathway of plant cells consists of several organelles that are connected by vesicle and tubular transport. Every compartment has a distinct function and the specificity of vesicle fusion is essential to maintain the organelles identity. N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) play a crucial role in the secretory pathway driving specific vesicle fusions. A vesicle SNARE (v-SNARE) on a vesicle specifically interacts with two or three target SNAREs (t-SNAREs) on the target compartment. This event leads to vesicle membrane fusion with the membrane of the target compartment and the release of cargo molecules into the organelle lumen.<p> The aim of this work was the characterization of two <i>Arabidopsis thaliana</i> SNAREs. The first one is a v-SNARE, Bet11 that is the Arabidopsis ortholog of the yeast and mammal ER-Golgi v-SNARE, Bet1. In these organisms, Bet1 is involved in trafficking between the ER and Golgi apparatus. The second protein studied is a putative SNARE called Bet12 that shares high sequence identity with Bet11. In particular, I was interested in studying the sorting of these two proteins and their role in the secretory pathway of plant cells. By confocal laser microscopy, I demonstrated that these two proteins have different intracellular localization: Bet11 was mainly localized on the ER, Golgi stacks and punctate structures that I have identified as endosomes. Bet12 was localized only on the Golgi stacks. The identification of signal(s) involved in targeting of Bet11 and Bet12 were studied. To reach this aim I generated different mutant chimeras of Bet11 and Bet12. The co-expression of these chimeras with specific protein markers suggested that the distribution of these proteins was the result of a combined influence of multiple domains.<p> A serine in the Bet11 sequence was identified as a putative phosphorylation site and appeared important for proper Bet11 intracellular distribution.<p> The different intracellular distributions of Bet11 and Bet12 suggest different biological roles for the two proteins. To functionally characterize these two proteins homozygous knock-down mutants of Bet11 were screened. These plants had no evident phenotype, suggesting a possible genetic redundancy in this SNARE family.

The secretory pathway of plant cells consists of several organelles that are connected by vesicle and tubular transport. Every compartment has a distinct function and the specificity of vesicle fusion is essential to maintain the organelles identity. N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) play a crucial role in the secretory pathway driving specific vesicle fusions. A vesicle SNARE (v-SNARE) on a vesicle specifically interacts with two or three target SNAREs (t-SNAREs) on the target compartment. This event leads to vesicle membrane fusion with the membrane of the target compartment and the release of cargo molecules into the organelle lumen.<p> The aim of this work was the characterization of two <i>Arabidopsis thaliana</i> SNAREs. The first one is a v-SNARE, Bet11 that is the Arabidopsis ortholog of the yeast and mammal ER-Golgi v-SNARE, Bet1. In these organisms, Bet1 is involved in trafficking between the ER and Golgi apparatus. The second protein studied is a putative SNARE called Bet12 that shares high sequence identity with Bet11. In particular, I was interested in studying the sorting of these two proteins and their role in the secretory pathway of plant cells. By confocal laser microscopy, I demonstrated that these two proteins have different intracellular localization: Bet11 was mainly localized on the ER, Golgi stacks and punctate structures that I have identified as endosomes. Bet12 was localized only on the Golgi stacks. The identification of signal(s) involved in targeting of Bet11 and Bet12 were studied. To reach this aim I generated different mutant chimeras of Bet11 and Bet12. The co-expression of these chimeras with specific protein markers suggested that the distribution of these proteins was the result of a combined influence of multiple domains.<p> A serine in the Bet11 sequence was identified as a putative phosphorylation site and appeared important for proper Bet11 intracellular distribution.<p> The different intracellular distributions of Bet11 and Bet12 suggest different biological roles for the two proteins. To functionally characterize these two proteins homozygous knock-down mutants of Bet11 were screened. These plants had no evident phenotype, suggesting a possible genetic redundancy in this SNARE family.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 102-112). Available also in a digital version from Dissertation Abstracts.

No description available.

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Young developing fruits of nasturtium (Tropaeolum majus L.) accumulate large deposits of non-fucosylated "storage" XG in periplasmic spaces of cotyledon cells. The only XG that is clearly fucosylated in these fruits Is the structural fraction (approx. 1% total) integrated into growing primary walk. Storage XG can be fucosylated by a nasturtium transferase in vitro, but this does not happen in vivo, even as a transitory signal required for secretion which would subsequently be cleaved to produce mature non-fucosylated storage XG in the periplasmic space. The two fucosylated subunits that are formed in vitro are identical to those found in structural XG in vivo. A block appears to develop in the secretory machinery of young cotyledon cells resulting in extended galactosylation and diversion of XG traffic to the periplasm without fucosylation. The primary walls buried beneath accretions of storage XG eventually swell and lose cohesion, probably because they continue to extend without incorporating components like fucosylated XG that are needed for maintaining wall integrity.

Thesis (Ph. D.)--Oregon Graduate Center, 1989.

Thesis (D. Sc.)--Faculty of Science, University of Adelaide, 1990. / Published works [representing] original research conducted during the various phases of [his] academic development--Pref. Includes bibliographical references.