Identification and modulation of a growth hormone-binding protein in rainbow trout (Oncorhynchus mykiss) plasma during seawater adaptation.
A soluble protein that specifically bound 125I-human growth hormone (hGH) was identified in rainbow trout plasma, using HPLC-gel filtration. The binding affinity of the protein for hGH was 1.2 x 10(9)M-1. 125I-rainbow trout GH (tGH) was also able to bind to the protein albeit with a lower affinity (6.6 x 10(7)M-1) than hGH. Crosslinking experiments using 125I-hGH revealed two specific bands of 150 and 130 kDa. The complex 125I-hGH-BP could be precipitated by a monoclonal anti-GH receptor antibody, suggesting a close relationship between the plasma GH-BP and the GH receptor. A fourfold increase in the hGH binding to the GH-BP was shown 48 h after transfer of the fishes from freshwater to seawater. The increase in binding was related to a high binding capacity without significant changes in binding affinity. These results suggest a potential role of this related GH-BP as an index of GH effects during seawater adaptation in salmonids.
Sohm
F
F
Unité 344, Endocrinologie moléculaire, Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine Necker, Paris Cedex 15, 75730, France.
Manfroid
I
I
Pezet
A
A
Rentier-Delrue
F
F
Rand-Weaver
M
M
Kelly
P A
PA
Boeuf
G
G
Postel-Vinay
M C
MC
de Luze
A
A
Edery
M
M
D000222:Adaptation, Physiological; D000818:Animals; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D029941:Fish Proteins; D006023:Glycoproteins / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism; D007457:Iodine Radioisotopes; D017686:Oncorhynchus mykiss / Q000097:blood*; D010907:Pituitary Hormones / Q000378:metabolism; D011233:Precipitin Tests; D011986:Receptors, Somatotropin / Q000378:metabolism; D011994:Recombinant Proteins; D012623:Seawater
D002352:Carrier Proteins; D029941:Fish Proteins; D006023:Glycoproteins; D007457:Iodine Radioisotopes; D010907:Pituitary Hormones; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; C064448:somatolactin protein, fish; D013006:Growth Hormone; C051815:somatotropin-binding protein