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[2] Regulation of hormone-sensitive lipase activity in adipose tissue

1997; Academic Press; Linguagem: Inglês

10.1016/s0076-6879(97)86004-1

1557-7988

Cecilia Holm, Dominique Langin, Vincent Manganiello, Per Belfrage, Eva Degerman,

Metabolism, Diabetes, and Cancer

Hormone-sensitive lipase (HSL) is known to be phosphorylated at two distinct serine residues, termed the regulatory and basal sites, respectively. cAMP-PK phosphorylates HSL at the regulatory site. Studies in isolated rat adipocytes have shown the extent of phosphorylation at the regulatory site correlates with the rate of lipolysis. The mechanism underlying activation through phosphorylation the regulatory site of HSL by cAMP-PK is poorly understood. The basal site of HSL is located only two amino acids C terminal of the regulatory site. Phosphorylation of this site occurs without any direct effect on enzyme activity. Studies in isolated rat adipocytes have indicated that the basal site is phosphorylated to a large extent in unstimulated cells. This, together with the observation that phosphorylation of the two sites seems to be mutually exclusive, suggests that phosphorylation of the basal site has an antilipolytic role in vivo, and that phosphorylation of the regulatory site by cAMP-PK has to be preceded by a dephosphorylation of the basal site.