Control of lipolysis in adipose cells by a cAMP-mediated cascade system

Hormonal activation of a b–adrenergic G-protein coupled receptor on the plasma membrane leads to elevation of cAMP levels, which in turn, activates protein kinase A (PKA).  PKA phosphorylates perilipin (PL) and HSL.

1. CGI-58 dissociates from phosphorylated-PL, and binds ATGL .

2. Phosphorylated HSL is recruited to the lipid droplet and activated by phosphorylated-PL.

3. Phosphorylated-PL also recruits the ATGL/CGI-58 complex to the lipid droplet, activating this lipase.

4. Activated ATGL hydrolyzes TG to activated HSL hydrolyzes DG to cytoplasmic MGL hydrolyzes MG to free glycerol + FFA.