Breakdown of phosphatidylinositol in soybean callus.

We have investigated the breakdown of membrane-bound phosphatidylinositol (PI) in homogenates of soybean (Glycine max) callus. The breakdown of PI was stimulated by the detergent deoxycholate. At pH 7.0 and 1·gl(-1) of deoxycholate the loss of PI was rapid and extensive: more than 80% was broken down within 10 min. The breakdown of PI was also stimulated by millimolar concentrations of Ca(2+). The products of breakdown of added PI (purified from soybean callus) in this system were identified from their chromatographic mobilities as 1,2-diacylglycerol, myo-inositol 1-phosphate and myo-inositol 1:2-cyclic monophosphate.