Addition of ammonium sulphate to nitrogen-depleted yeast cells resulted in a transient increase in Ins(1,4,5)P-3, with a maximum concentration reached after 7-8 min, as determined by radioligand assay and confirmed by chromatography. Surprisingly, the transient increase in Ins(1,4,5)P-3 did not trigger an increase in the concentration of intracellular calcium, as determined in vivo using the aequorin method. Similar Ins(1,4,5)P-3 signals were also observed in wild-type cells treated with the phospholipase C inhibitor 3-nitrocoumarin and in cells deleted for the only phospholipase C-encoding gene in yeast, PLC1. This showed clearly that Ins(1,4,5)P-3 was not generated by phospholipase C-dependent cleavage of PtdIns(4,5)P-2. Apart from a transient increase in Ins(1,4,5)P-3, we observed a transient increase in PtdIns(4,5)P2 after the addition of a nitrogen source to nitrogen-starved glucose-repressed cells. Inhibition by wortmannin of the phosphatidylinositol 4-kinase, Stt4, which is involved in PtdIns(4,5)P-2 formation, did not affect the Ins(1,4,5)P-3 signal, but significantly delayed the PtdIns(4,5)P-2 signal. Moreover, wortmannin addition inhibited the nitrogen-induced activation of trehalase and the subsequent mobilization of trehalose, suggesting a role for PtdIns(4,5)P-2 in nitrogen activation of the fermentable-growth-medium-induced signalling pathway.
http://hdl.handle.net/10281/12977
Citazione: | Bergsma, J., Kasri, N.N., Donaton, M., De Wever, V., Tisi, R.A., de Winde, J.H., et al. (2001). PtdIns(4,5)P-2 and phospholipase C-independent Ins(1,4,5)P-3 signals induced by a nitrogen source in nitrogen-starved yeast cells. BIOCHEMICAL JOURNAL, 359, 517-523. |
Tipo: | Articolo in rivista - Articolo scientifico |
Carattere della pubblicazione: | Scientifica |
Titolo: | PtdIns(4,5)P-2 and phospholipase C-independent Ins(1,4,5)P-3 signals induced by a nitrogen source in nitrogen-starved yeast cells |
Autori: | Bergsma, JCT; Kasri, NN; Donaton, MCV; De Wever, V; Tisi, RA; de Winde, JH; Martegani, E; Thevelein, JM; Wera, S |
Autori: | |
Data di pubblicazione: | 1-nov-2001 |
Lingua: | English |
Rivista: | BIOCHEMICAL JOURNAL |
Digital Object Identifier (DOI): | 10.1042/0264-6021:3590517 |
Appare nelle tipologie: | 01 - Articolo su rivista |