When Chlamydomonas eugametos gametes were incubated in carrier-free [32P]P1, the label was rapidly incorporated into PtdInsP and PtdInsP2 and, after reaching a maximum within minutes, was chased out by recirculating unlabelled P1 in the cell. This pulse-chase labelling pattern reflects their rapid turnover. In contrast, 32P incorporation into the structural lipids was slow and continued for hours. Of the radioactivity in the PtdInsP spot, 15% was in PtdIns3P and the rest in PtdIns4P, and of that in the PtdInsP2 spot, 1% was in PtdIns(3,4)P2 and the rest in PtdIns(4,5)P2, confirming the findings by Irvine, Letcher, Stephens and Musgrave [(1992) Biochem. J. 281, 269-266]. When cells were labelled with carrier-free [32P]P1, both PtdInsP isomers incorporated label in a pulse-chase-type pattern, demonstrating for the first time in a plant or animal system that D-3 poly-phosphoinositides turn over rapidly in non-stimulated cells, with kinetics similar to those shown by the D-4 isomers. In animal systems such lipids are already established as signalling molecules, and the data suggest that a similar role must be sought for them in lower plants such as Chlamydomonas.
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March 1994
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Research Article|
March 01 1994
Rapid turnover of phosphatidylinositol 3-phosphate in the green alga Chlamydomonas eugametos: signs of a phosphatidylinositide 3-kinase signalling pathway in lower plants?
T Munnik;
T Munnik
*Institute for Molecular Cell Biology, BioCentrum, University of Amsterdam, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands
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R F Irvine;
R F Irvine
†Deparment of Biochemistry, AFRC Institute, Babraham, Cambridge CB2 4AT, U.K.
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A Musgrave
A Musgrave
*Institute for Molecular Cell Biology, BioCentrum, University of Amsterdam, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1994 The Biochemical Society, London
1994
Biochem J (1994) 298 (2): 269–273.
Citation
T Munnik, R F Irvine, A Musgrave; Rapid turnover of phosphatidylinositol 3-phosphate in the green alga Chlamydomonas eugametos: signs of a phosphatidylinositide 3-kinase signalling pathway in lower plants?. Biochem J 1 March 1994; 298 (2): 269–273. doi: https://doi.org/10.1042/bj2980269
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