The availability of endogenous and exogenous disaturated diacylglycerol for the diacylglycerol-consuming reactions in lung microsomes.

Lung tissue is characterized by its high level of dipalmitoylphosphatidylcholine, which can be synthesized by lung microsomes with endogenous and exogenous 1,2-dipalmitoylglycerol as the substrate. This endogenous substrate species was also available for the triacylglycerol synthesis but not for the de novo synthesis of phosphatidylethanolamine. From exogenous disaturated diacylglycerol the corresponding species of phosphatidylcholine, triacylglycerol and also phosphatidylethanolamine were formed. These results support the thesis that endogenous disaturated diacylglycerol is not available for all diacylglycerol-consuming reactions.