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The lysolipid sphingosine modulates pyrophosphatase activity in tonoplast vesicles and isolated vacuoles from a heterotrophic cell suspension culture of Chenopodium rubrum
Author(s) -
Bille Joachim,
Weiser Thomas,
Bentrup FriedrichWilhelm
Publication year - 1992
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1992.tb04661.x
Subject(s) - vacuole , biochemistry , sphingosine , vesicle , biology , inorganic pyrophosphatase , pyrophosphatase , atpase , sphingosine kinase , enzyme , membrane , pyrophosphate , sphingosine 1 phosphate , receptor , cytoplasm
The proton pumping activity of the tonoplast (vacuolar membrane) H + ‐ATPase and H + ‐pyrophosphatase (H + ‐PPase) has been studied on a tonoplast‐enriched microsomal fraction and on intact vacuoles isolated from a heterotrophic cell suspension culture of Chenopodium rubrum L. in the presence of the lysosphingolipids D‐sphingosine, psychosine (galactosylsphingosine) and lysosulfatide (sulfogalactosyl‐sphingosine). Sphingosine strongly stimulates (K a = 0.16 μ M ) the PPase activity, assayed both as ΔpH formation across the tonoplast vesicle membrane, and as reversible clamp current measured by the whole‐vacuolar mode of the patch‐clamp technique. Psychosine showed a minor, and lysosulfatide no stimulatory effect. No effect upon the ATPase activity has been observed. No sphingosine‐induced change could be observed in the affinity of the PPase for its substrate (apparent K m = 10 μ M MgPPi). We tentatively conclude that sphingosine, which is known as a potent inhibitor of the protein kinase C in animal cells, may be a regulator of the plant vacuolar PPase.