title: Growth hormone (GH) and estradiol regulation of membrane-associated GH binding protein and GH receptors in GH releasing hormone transgenic mice.
abstract: Growth hormone (GH) releasing hormone (GHRH) transgenic mice were used to examine the influence of GH on GH receptor (GHR) and membrane-associated GH binding protein (MA-GHBP) levels by means of specific radioimmunoassays and Western blot analysis, since MA-GHBP was described as the major constituent of somatogenic binding to liver membranes in mice. In transgenic animals, a 10-fold increment over normal values was found for hepatic somatogenic binding that could be accounted for by a 3--4-fold increase in GHR and a 9-fold augmentation of MA-GHBP levels. The apparent molecular weight of MA-GHBP was smaller than that of serum GHBP, a difference that was partially abolished by endoglycosidase F digestion. In vivo treatment of female mice with 17 beta-estradiol led to an unexpected down-regulation of MA-GHBP and GHR by 60--75% only in transgenic animals. MA-GHBP and GHR levels are strongly up-regulated by GH, although MA-GHBP up-regulation is much more important than that of GHR.
authors: Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquímica, Junín 956, Buenos Aires, Argentina.
authors: L
authors: L
authors: González
authors: A I
authors: AI
authors: Sotelo
authors: A
authors: A
authors: Bartke
authors: D
authors: D
authors: Turyn
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics*; D022781:Hepatocytes / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008862:Microsomes, Liver / Q000378:metabolism; D011863:Radioimmunoassay; D011986:Receptors, Somatotropin / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D004958:Estradiol; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; C051815:somatotropin-binding protein