title: Identification of second lipolysis activating protein from scorpion Buthus occitanus tunetanus.
abstract: Besides the previously described LVP1, a second protein, LVP2, inducing a lipolytic response in adipose cells, was purified from scorpion Buthus occitanus tunetanus venom. It represented 2% of crude venom proteins, with pHi = 6 and molecular mass of 16889 Da. The reduction and the alkylation of LVP2 revealed an heterodimeric structure. Isolated alpha and beta chains of LVP2 have a molecular weight (MW) of 8822 Da and 8902, respectively. This protein was not toxic to mice and stimulated lipolysis on freshly dissociated rat adipocytes in a dose-dependent manner with EC50 = 2 +/- 0.75 microg/ml. LVP2 subunits did not display any lipolytic activity. As previously described for venom and LVP1, beta adrenergic receptor (beta AR) antagonists interfere with LVP2 activity. Furthermore, it is shown that LVP2 competes with [3H] CGP 12177 (beta1/beta2 AR antagonist) for binding to adipocyte plasma membrane with an IC50 of about 10(-7)M. Thus, these results bring original information on the existence of proteins that are present in scorpion venoms and can exert a distinct biological activity on adipocyte lipolysis through a beta-type adreno-receptor pathway.
authors.affiliation: Laboratoire des venins et toxines, Institut Pasteur de Tunis, BP 74-1002 Tunis, Tunisie.
authors.forename: N
authors.initials: N
authors.lastname: Soudani
authors.forename: J
authors.initials: J
authors.lastname: Gharbi-Chihi
authors.forename: N
authors.initials: N
authors.lastname: Srairi-Abid
authors.forename: H
authors.initials: H
authors.lastname: Kaabi
authors.forename: A
authors.initials: A
authors.lastname: Margotat
authors.forename: J
authors.initials: J
authors.lastname: Torresani
authors.forename: M
authors.initials: M
authors.lastname: El Ayeb
mesh_terms: D017667:Adipocytes; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000478:Alkylation; D000818:Animals; D001681:Biological Assay; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006863:Hydrogen-Ion Concentration; D036341:Intercellular Signaling Peptides and Proteins; D007525:Isoelectric Focusing; D007928:Lethal Dose 50; D008066:Lipolysis / Q000502:physiology; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D010455:Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D012604:Scorpion Venoms / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity
chemical_list: D000319:Adrenergic beta-Antagonists; D036341:Intercellular Signaling Peptides and Proteins; C498242:LVP1 peptide, Buthus occitanus tunetanus; C513702:LVP2 peptide, Buthus occitanus tunetanus; D010455:Peptides; D011412:Propanolamines; D012604:Scorpion Venoms; C033394:CGP 12177