title: Specificity of covalently stabilized complexes of 125I-labeled human somatotropin and components of the lactogenic binding sites of rat liver.
abstract: 125I-labeled human somatotropin specifically bound to the lactogenic sites of microsomal membranes from pregnant rat liver, originated a radioactive covalent complex of Mr 63,000 upon reaction with dimethyl suberimidate, disuccinimidyl suberate (DSS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The amount of this species was closely parallel with the preexisting amount of the ligand-receptor complex. Photoactivation of a hormone derivative bound to the receptor also gave rise to the 63 K species. A ternary complex of receptor, hormone and Triton X-100 cross-linked with DSS yielded the 63 K species and a new one of 96 K. The data indicate that the 63 K complex involves the radioactive hormone and a constituent of the binding site. The 96 K species could comprise a second component of the receptor.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D010928:Placental Lactogen / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D018000:Receptors, Peptide
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D018000:Receptors, Peptide; C028202:placental lactogen receptor; D013006:Growth Hormone; D010928:Placental Lactogen