Activation of hormone-sensitive lipase from adipose tissue by cyclic AMP-dependent protein kinase

Lipase activation requiring cyclic-3′,5′-adenosine monophosphate and ATP was demonstrated in crude fractions of human adipose tissue homogenates. Activation was totally blocked by addition of the specific protein kinase inhibitor. Levels of endogenous protein kinase were adequate to support clear-cut activation but in partially purified preparations addition of exogenous (rabbit muscle) kinase further enhanced activation. When tissue was treated with epinephrine prior to homogenization the degree of activation in partially purified fractions was distinctly reduced. The mechanism of activation of hormone-sensitive lipase in human adipose tissue is thus shown, like that in rat adipose tissue, to be linked to a cyclic AMP-dependent protein kinase.