ISSN:
1432-2048
Keywords:
Dianthus
;
Phosphatidylinositol 3-phosphate
;
Phospholipid turnover
;
Polyphosphoinositides
;
Signal transduction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Carnation (Dianthus caryophyllus L. cv. White Sim) petal discs were radiolabelled with [32P]orthophosphate and the lipids were extracted and analysed by thin-layer chromatography and autoradiography. Phospholipids were identified by co-migration with standards using thin-layer chromatography with different solvent systems. Results showed that [32P]orthophosphate was rapidly incorporated into the minor lipids phosphatidic acid (PtdOH), phosphatidylinositol monophosphate (PtdInsP) and phosphatidylinositol bisphosphate (PtdInsP2), and relatively slowly into the structural lipids phosphatidylcholine, -ethanolamine, -glycerol and -inositol. Pulse-chase experiments revealed that the label was rapidly lost from PtdOH, PtdInsP and PtdInsP2 while the structural lipids remained radiolabelled. The amount of PtdInsP and PtdInsP2 was found to constitute 0.45% and 0.013%, respectively, of the total phospholipids, on a molar basis. Together these results show that the turnover of the chemically low-abundant polyphosphoinositides is relatively high compared with the major structural phospholipids. Phosphatidylinositol monophosphate was further characterized by showing that it incorporates myo[3H]inositol and that its major fatty-acid constituents are palmitic acid and linoleic acid. Furthermore, we present evidence for the presence of both phosphatidylinositol 3-phosphate and phosphatidylinositol 4-phosphate isomers. The significance of these results is discussed with respect to plant phosphoinositide signal transduction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00191611
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