title: Structural characterization of the somatostatin receptor in rat anterior pituitary membranes.
abstract: To structurally characterize the somatostatin receptor in the anterior pituitary, the chemical cross-linking reagent N-5-azido-nitrobenzoyloxysuccinimide was used to attach covalently [125I-Tyr11]somatostatin-14 to its receptor in pituitary membranes. Rat anterior pituitary membranes were incubated with [125I-Tyr11]somatostatin-14, washed, and then treated with 100 microM cross-linker, which was activated by exposure to UV light. Gel electrophoresis followed by autoradiography revealed a broad band centered at 88,000 mol wt. The appearance of this band was unaffected by dithiothreitol. Competitive inhibition of binding by unlabeled somatostatin resulted in a parallel inhibition of labeling of the 88,000 mol wt protein. The addition of guanine nucleotides in concentrations that inhibit binding similarly inhibited cross-linking. The cross-linked membranes were solubilized in Zwittergent 3-12, a nondenaturing detergent, and the glycosylation pattern of the labeled protein was investigated by incubation with various lectins coupled to agarose. The cross-linked protein was selectively adsorbed by wheat germ agglutinin, and this interaction was blocked by the addition of N,N',N"-triacetylchitotriose, indicating that the rat anterior pituitary somatostatin receptor is a glycoprotein containing polymeric beta-1-4 linked N-acetylglucosamine groups. The results of this study show that the rat anterior pituitary somatostatin receptor is a glycoprotein of 88,000 mol wt containing no disulfide-linked subunits.
mesh_terms: D000327:Adsorption; D000818:Animals; D001386:Azides; D002462:Cell Membrane / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D003432:Cross-Linking Reagents; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D037102:Lectins; D008297:Male; D008970:Molecular Weight; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism*; D017481:Receptors, Somatostatin; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism; D013388:Succinimides; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D001386:Azides; D003432:Cross-Linking Reagents; D037102:Lectins; D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; D013388:Succinimides; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013004:Somatostatin; C032367:somatostatin, Tyr(11)-; C049915:N-hydroxysuccinimidyl-5-azido-2-nitrobenzoate; D006160:Guanosine Triphosphate