Evidence for a multi-domain structure for hormone-sensitive lipase.
Hormone-sensitive lipase (HSL) is a multi-functional enzyme involved in several aspects of lipid metabolism. Limited tryptic digestion of HSL led to selective loss of activity against lipid substrates but not against the water-soluble substrate, p-nitrophenyl butyrate. Following labelling of the active site of HSL with either [3H]di-isopropylfluorophosphate or [14C]orlistat, tryptic digestion of HSL generated a stable radiolabelled domain of molecular mass approx. 17.6 kDa, consistent with this representing a catalytic domain of HSL capable of hydrolysing water-soluble but not lipid substrates. Following phosphorylation of HSL by cyclic AMP-dependent protein kinase, limited tryptic digestion produced a stable phosphorylated domain of molecular mass 11.5 kDa. Based on these experimental data a model for a domain structure of HSL is proposed.
Department of Biochemistry and Genetics, Medical School, University of Newcastle, Newcastle upon Tyne, UK.
G M
GM
Smith
A J
AJ
Garton
A
A
Aitken
S J
SJ
Yeaman
D000595:Amino Acid Sequence; D001665:Binding Sites; D002087:Butyrates / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D007783:Lactones / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D000077403:Orlistat; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D002787:Sterol Esterase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism
D002087:Butyrates; D004791:Enzyme Inhibitors; D007783:Lactones; D010446:Peptide Fragments; C033592:4-nitrophenyl butyrate; D000077403:Orlistat; D002787:Sterol Esterase; D014357:Trypsin