title: Effects of different radioligands on the antigen binding specificity of somatostatin antisera.
abstract: The regions of the somatostatin (SRIF) molecule recognized by five antisera were systematically studied using three radioligands (125I-N-Tyr-SRIF, [125I-Tyr1]-SRIF and [125I-Tyr11]- SRIF) and SRIF analogs containing sequential substitutions with alanine or tyrosine. Antisera SA and moreso SB had N-terminal specificity when used with [125 I-Tyr11]-SRIF but central molecular specificity when studied with the two N-terminal radiolabelled analogs. The N-terminal and central specific populations of antibodies in antiserum SB were separable by immunoaffinity adsorption using immobilized [Tyr1]-SRIF. It is of practical significance that the same antiserum (SB) could be used with different radioligands to perform N-terminal and central specific radioimmunoassays (RIAs). The central specific RIA detected SRIF-14 and SRIF-28 on an approximately equimolar basis whereas the N-terminal specific RIA was selective for SRIF-14.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D001667:Binding, Competitive; D000939:Epitopes; D008024:Ligands; D009842:Oligopeptides / Q000276:immunology; D012756:Sheep; D013004:Somatostatin / Q000276:immunology*
chemical_list: D000939:Epitopes; D008024:Ligands; D009842:Oligopeptides; D013004:Somatostatin