학술논문

Solubilization and characterization of guinea-pig pancreatic somatostatin receptors.
Document Type
Article
Source
European Journal of Biochemistry. 5/4/87, Vol. 164 Issue 3, p667-673. 7p.
Subject
*SOMATOSTATIN
*GASTROINTESTINAL hormones
*ISLANDS of Langerhans
*HYPOTHALAMIC hormones
*GUINEA pigs
*DIGESTIVE enzymes
Language
ISSN
0014-2956
Abstract
The solubilization of somatostatin receptors from guinea-pig pancreas by different non-denaturing detergents was investigated after stabilization of the receptors by prior binding of 125I-[Tyr11]somatostatin or its analogue 125I-[Leu8,DTrp22,Tyr25]somatostatin 28, to pancreatic plasma membranes. The somatostatin-receptor complexes were solubilized in a high yield by Zwittergent 3-14 (3-[tetradecyldimethylammonio]-1-propanesulfonate), a zwitterionic detergent. Other detergents, digitonin, Triton X-100, Chaps (3[cholamidopropyldimethylammonio]-1-propanesulfonate) and octyl β-D-glycopyranoside, achieved only partial solubilization. The recovery of receptor complexes was increased by glycerol. In order to characterize solubilized somatostatin-receptor complexes, membranes receptors were covalently labelled using N-5-azido-2-nitrobenzoyloxysuccinimide as cross-linking reagent before solubilization. Gel filtration chromatography analysis resulted in the identification of a major protein component of apparent Mr = 93 000 which interacted with the two radioligands. In addition, a similar component of Mr = 88 000 was characterized after analysis by SDS-PAGE of membrane receptors covalently cross-linked with 125I-[Leu8,DTrp22,Tyr25]somatostatin 28 by different heterobifunctional reagents: N-5-azido-2-nitrobenzoyloxysuccinimide, N-hydroxysuccinimidyl 4-azidobenzoate, N-succinimidyl 6(4'-azido-2'-nitrophenylamino)hexanoate. Optimal cross-linking results were obtained with N-5-azido-2nitrobenzoyloxysuccinimide. The solubilized somatostatin-receptor complex was adsorbed to wheat-germ agglutinin-agarose column and eluted by specific sugars. We concluded that the guinea-pig pancreatic somatostatin receptor in the membrane and in the non-denaturing detergent solution behaves as a protein monomer of apparent Mr ≈ 85 000-90 000. The somatostatin receptor is a glycoprotein which contains complex-type carbohydrate chains. [ABSTRACT FROM AUTHOR]