Identification of Ca2+-stimulated polyphosphoinositide phospholipase C in isolated plant plasma membranes.
A polyphosphoinositide phospholipase C has been identified in highly purified plasma membranes from shoots and roots of wheat seedlings. The enzyme preferentially hydrolysed phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate and had a different phosphoinositide substrate profile from soluble phospholipase C. The enzyme activity was lower in plasma membranes isolated from light-grown shoots than from dark-grown ones, whereas no differences in activity between plasma membranes from light- and dark-grown roots were seen. Maximum activity of the membrane-bound enzyme was observed around pH 6. It was activated by micromolar concentrations of Ca2+, but not by GTP or GTP analogues. The enzyme may participate in signal transduction over the plant plasma membrane.
Melin
P M
PM
Department of Biochemistry, Chemical Centre, Lund, Sweden.
Sommarin
M
M
Sandelius
A S
AS
Jergil
B
B
D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007295:Inositol Phosphates / Q000502:physiology; D007700:Kinetics; D010716:Phosphatidylinositols / Q000502:physiology*; D014908:Triticum; D010738:Type C Phospholipases / Q000378:metabolism*
D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D010738:Type C Phospholipases; D002118:Calcium