Hormonal Control of Adipose Tissue Lipolysis by Phosphorylation/Dephosphorylation of Hormone-Sensitive Lipase
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The quantitatively most important energy substrate in mammals are free fatty acids (FFA), stored as triacylglycerol in the adipocytes. Hormones and the sympathetic nervous system regulate the mobilization of FFA from the adipose tissue, and the rate of this process mainly reflects the hydrolysis of the intracellular triacylglycerols, in the process of adipose tissue lipolysis. Fast-acting lipolytic hormones increase, and insulin inhibits this lipolysis by controlling the activity of the hormone-sensitive lipase (HSL), the rate-limiting enzyme. The lipase catalyzes hydrolysis of the first ester bond of the triacylglycerol substrate, which is the rate-limiting step of fat breakdown, and also the degradation of the 1,2 (2,3)-diacylglycerols to 2-monoacylglycerols. The final hydrolysis of the monoacylglycerols to FFA and glycerol is catalyzed by a separate monoacylglycerol lipase (15).
KeywordsHormonal Control Reversible Phosphorylation Cholesterol Ester Hydrolase Adipose Tissue Lipolysis Monoacylglycerol Lipase
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