Generation of Chicken Growth Hormone-Binding Proteins by Proteolysis

• Published in: General and comparative endocrinology Vol. 113; no. 2; pp. 283 - 289
• Main Authors: Vleurick, L., Kühn, E.R., Decuypere, E., Burnside, J., Pezet, A., Edery, M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.1999
• Subjects: Animals; binding protein; BINDING PROTEINS; Binding, Competitive - physiology; Carrier Proteins - biosynthesis; Cercopithecus aethiops; CHICKENS; Chromatography, Gel; Chromatography, High Pressure Liquid; COS Cells; CRECIMIENTO; CROISSANCE; Cross-Linking Reagents - chemistry; Culture Media; Cytosol; Electrophoresis, Polyacrylamide Gel; generation (chicken); GROWTH; growth hormone; Growth Hormone - chemistry; HORMONAS; HORMONE; HORMONES; Peptide Hydrolases - metabolism; POLLO; POULET; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; PROTEOLISIS; PROTEOLYSE; PROTEOLYSIS; Receptors, Somatotropin - analysis; Scintillation Counting; Transfection - physiology; growth hormone; generation (chicken); binding protein; proteolysis
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1006/gcen.1998.7202

A soluble protein that specifically bound growth hormone (GH) was characterized in culture medium of a COS-7 cell line transfected with the cDNA of the full-length chicken GH receptor (cGHR). Incubation of culture medium with125I-labeled human GH resulted in the formation of a single specific complex with high affinity (KD= 0.36 nM) and apparent molecular weight of 75 kDa. The production of large quantities of GH-binding protein (GHBP) amounting to, per hour, 23% of the cell's GHR, points to the importance of partial proteolysis for GHR turnover. Considerable amounts of GHBP were also detected in a cytosolic fraction. These results strongly suggest that in chicken, as in rabbit and monkey, the GHBP is generated, at least partially, by proteolytic cleavage of the membrane-anchored GHR.