Identification and characterization of growth hormone receptors in snakehead fish (Ophiocephalus argus cantor) liver.
The specific binding of 125I-labeled fish growth hormone (GH) to hepatic membranes prepared from several freshwater fish was assessed. A high level of growth hormone receptor (GHR) was detected on the hepatic membranes of the snakehead fish (Ophiocephalus argus Cantor). Scatchard analysis of the binding data showed a single class of high affinity binding site with a binding affinity (Ka) of 1.45 +/- 0.23 x 10(9) M-1 and a binding capacity (Bmax) of 198 +/- 57 fmol/mg protein. The binding was specific for fish GH and was saturable. In addition, the specific binding was temperature- and time-dependent, reaching a steady state after 16 hr of incubation at 25 degrees . The molecular weight of GHR as measured by Sephadex G-200 column chromatography and Western blot analysis using a monoclonal antibody (Mab263) against GHR was found to be 200-400 and 90-93 kDa, respectively. Two bands at 65 and 89 kDa were identified in ligand crosslinking studies of membrane receptors. A sensitive teleost GH radioreceptor assay (RRA) was developed, using recombinant fish GH and a membrane preparation from snakehead fish liver, capable of measuring bioactive GH in fish sera or other samples.
Sun
X
X
Shanghai Institute of Biochemistry, Academia Sinica, Shanghai, 200031, China.
Zhu
S
S
Chan
S S
SS
Toresson
G
G
Cheng
C H
CH
D000818:Animals; D015153:Blotting, Western; D002850:Chromatography, Gel; D005260:Female; D005399:Fishes / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism; D019382:Human Growth Hormone / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000378:metabolism; D011485:Protein Binding; D011869:Radioligand Assay; D011986:Receptors, Somatotropin / Q000737:chemistry / Q000378:metabolism*
D011986:Receptors, Somatotropin; D019382:Human Growth Hormone; D013006:Growth Hormone