Role of the alkaline TG lipase in regulating intramuscular TG content.

Three TG lipases have been identified in muscle (i.e., acid, neutral, and alkaline), but as yet we do not know which enzyme is responsible for tissue TG hydrolysis. Over the past 8 yr, work in our laboratory has focused on intracellular lipoprotein lipase (LPL). The results show that this lipase is regulated by the classical cAMP cascade and that the activity of this enzyme is inversely related to endogenous TG concentration. Using these results as a foundation we plan to examine molecular mechanisms involved in the synthesis, compartmentalization, and transport of the alkaline TG lipase. Further, the evidence suggests that this enzyme may be regulated by protein phosphorylation mediated by cyclic AMP-dependent protein kinase. We plan to test this possibility.