Polyphosphoinositide phospholipase C and evidence for inositol-phosphate-hydrolysing activities in the plasma-membrane fraction from light-grown wheat (Triticum aestivum L.) leaves

Autor: Michael C. Arz, Hans J. Grambow
Rok vydání: 1994
Předmět:
Zdroj: Planta. 195
ISSN: 1432-2048
0032-0935
DOI: 10.1007/bf00206292
Popis: The phospholipase C (PLC; EC 3.1.4.3) activity in isolated plasma membranes of light-grown wheat (Triticum aestivum L. cv. Prelude) leaves was investigated. The activity against the polyphosphoinositides was strongly dependent on Ca2+ and was affected by the anionic detergent deoxycholate (DOC). In the presence of 20 μM Ca2+ the PLC activity preferred phosphatidylinositol 4,5-bisphosphate (PIP2) over phosphatidylinositol 4-monophosphate (PIP) as a substrate. Instead, with 1 mM Ca2+ the enzyme clearly favoured PIP. In addition, the PIP2-PLC activity was increased by Mg2+ and in the presence of GTP, guanosine 5′-(γ-thio)-triphosphate as well as ATP, CTP, guanosine 5′-diphosphate and guanosine 5′-(β-thio)-diphosphate. Further analysis showed that a molybdate-sensitive phosphatase activity catalysing the dephosphorylation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) is also associated with the plasma-membrane vesicles. Dephosphorylation of Ins(1,4,5)P3 was reduced in the presence of GTP or by inclusion of the unspecific phosphatase inhibitor molybdate. The results indicate the presence of a PIP2-PLC activity and the presence of a molybdate-sensitive phosphatase activity in wheat plasma-membrane vesicles.
Databáze: OpenAIRE
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