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.
Unité 344, Endocrinologie moléculaire, Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine Necker, Paris Cedex 15, 75730, France.
F
F
Sohm
I
I
Manfroid
A
A
Pezet
F
F
Rentier-Delrue
M
M
Rand-Weaver
P A
PA
Kelly
G
G
Boeuf
M C
MC
Postel-Vinay
A
A
de Luze
M
M
Edery
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