methionine synthase homolog is associated with secretory vesicles in tobacco pollen tubes

Seven isoforms of 85 kDa polypeptides (p85) were identified as methionine synthase (MetE) homologs by partial aminoacid sequencing in tobacco pollen tube extracts. Immunocytochemistry data showed a localization of the antigen on the surface of tip-focussed post-Golgi secretory vesicles (SVs), that a...

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Bibliographic Details
Published in:Planta 2005-08, Vol.221 (6), p.776-789
Main Authors: Moscatelli, A, Scali, M, Prescianotto-Baschong, C, Ferro, M, Garin, J, Vignani, R, Ciampolini, F, Cresti, M
Format: Article
Language:English
Subjects:
5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase - metabolism
Agronomy. Soil science and plant productions
Amino Acid Sequence
amino acid sequences
Antibodies
Antiserum
Biological and medical sciences
Centrifugation
Cytoplasm
Economic plant physiology
Flowering, floral biology, reproduction patterns
Fluorescent antibody techniques
Fundamental and applied biological sciences. Psychology
Gels
Growth and development
Isoenzymes
methionine
methionine synthase
methyltransferases
microtubules
Molecular Sequence Data
Nicotiana - enzymology
Nicotiana - ultrastructure
Nicotiana tabacum
Organelles
plant biochemistry
Plant cells
Plant Proteins
Pollen
Pollen - enzymology
Pollen - ultrastructure
Pollen tubes
polypeptides
Protein isoforms
Secretory Vesicles - enzymology
Secretory Vesicles - ultrastructure
sequence alignment
Sequence Homology, Amino Acid
tobacco
Western blotting
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Summary:Seven isoforms of 85 kDa polypeptides (p85) were identified as methionine synthase (MetE) homologs by partial aminoacid sequencing in tobacco pollen tube extracts. Immunocytochemistry data showed a localization of the antigen on the surface of tip-focussed post-Golgi secretory vesicles (SVs), that appear to be partially associated with microtubules (Mts). The chemical dissection of pollen tube high speed supernatant (HSS) showed that two distinct pools of MetE are present in pollen tubes, one being the more acidic isoforms sedimenting at 15S and the remaining at 4S after zonal centrifugation through a sucrose density gradient. The identification of the MetE within the pollen tube and its possible participation as methyl donor in a wide range of metabolic reactions, makes it a good subject for studies on pollen tube growth regulation.
ISSN:0032-0935
1432-2048
DOI:10.1007/s00425-005-1487-7