Purification of liver cytosolic proteins that stimulate triacylglycerol synthesis.

Heat-stable rat liver cytosolic proteins that stimulate triacylglycerol synthesis catalyzed by adipose tissue or liver microsomal enzymes have been isolated in a highly purified state. Their molecular weight ranges were found to be 35 000 - 45 000, 20 000 - 28 000, and 8000 - 12 000. The protein with molecular weight 20 000 - 28 000 and pI 7.3-7.7 was purified 4716-fold. The cytosolic proteins were stable at 85 degrees C for 15 min and were inactivated by proteases. They did not reveal any intrinsic phosphatidate phosphohydrolase or diacylglycerol acyltransferase activity, but led to enhanced conversion of phosphatidate to diacylglycerol and triacylglycerol.