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Updated: Jul 19, 2026
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Investigating Mast Cell Secretory Granules; from Biosynthesis to Exocytosis
Published on: January 26, 2015
Secretion marker proteins and cell-wall polysaccharides move through different secretory pathways
Maria Rosaria Leucci1, Gian-Pietro Di Sansebastiano, Massimiliano Gigante
1Di.S.Te.B.A., Università di Lecce, via prov.le Lecce-Monteroni, 73100 Lecce, Italy.
Planta
|October 14, 2006
Summary
Plant cell wall synthesis relies on the secretory pathway. Syntaxin NtSyr1 (Sp1) and its inhibitor Sp2 affect protein secretion but not polysaccharide incorporation into cell walls, suggesting distinct secretion mechanisms.
Area of Science:
- Plant Biology
- Cell Biology
- Molecular Plant Science
Background:
- The cell wall's construction is crucial for plant growth and depends on the secretory pathway.
- Syntaxins and SNARE proteins are vital for vesicle transport, secretion, and fusion processes.
Purpose of the Study:
- To investigate the roles of syntaxin homologue NtSyr1 (Sp1) and its inhibitor Sp2 in the secretion of cell wall polysaccharides and marker proteins.
- To compare the secretion pathways for cell wall matrix polysaccharides and secretory proteins in Nicotiana tabacum.
Main Methods:
- Transient transformation of protoplasts with secreted green-fluorescent protein (sec-GFP) and syntaxin variants (Sp1, Sp2).
- Quantification of sec-GFP and secreted rat preputial beta-glucuronidase (secRGUS) secretion.
- Analysis of newly synthesized polysaccharide incorporation into regenerating cell walls in protoplasts and roots.
- Treatment with cytochalasin D (CD) to assess its impact on secretion.
Main Results:
- Overexpression of Sp1 did not affect sec-GFP secretion, while Sp2 expression led to GFP accumulation within cells and reduced secRGUS secretion by 53%.
- Sp1 and Sp2 did not significantly alter the incorporation of newly synthesized polysaccharides into cell walls in protoplasts or roots.
- Cytochalasin D inhibited polysaccharide incorporation and secRGUS secretion, increasing membrane-associated polysaccharides.
Conclusions:
- Secretory marker proteins and cell wall matrix polysaccharides utilize distinct export machineries.
- Syntaxin Sp1 and its inhibitor Sp2 primarily impact protein secretion, not polysaccharide cell wall deposition.
- The secretory pathway for cell wall components differs from that of secretory proteins and cellulose synthase complexes.
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