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ISSN 1672-9145 Acta Biochim Biophys Sin 2004, 36(12): 811–816 CN 31-1940/Q

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Identification and Characterization of GH Receptor and Serum GH-binding Protein in Chinese Sturgeon (Acipenser sinensis)

Zhi-Yong LIAO^1,2 and Shang-Quan ZHU²*

¹College of Life Sciences, Jiangxi Normal University, Nanchang 330027, China;

²Key Laboratory of Proteomics Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China

Abstract Chinese sturgeon, a kind of cartilage ganoid, has a history of over one billion years and it is called the living fossil of aquatic biology since it keeps some evolutionary trace. Here, we characterized the growth hormone receptor (GHR) and serum growth hormone binding protein (GHBP) of Chinese sturgeon. It was shown that GHR was expressed in various tissues, mainly in hepatic, kidney and intestine tissues. GHR on the hepatic membrane has high and specific affinity for bream GH (brGH) and Scatchard analysis of the binding data showed a single class of high affinity binding site with an association constant Ka of 3.1´109 M1. A specific band around 94 kD was detected by SDS-PAGE in cross-linking studies of membrane receptors. After incubation of Chinese sturgeon serum with 125I-brGH, a 125I-brGH-GHBP complex was identified by Sephadex G-75, indicating that in the serum exists GHBP specially binding to brGH.

Key words Chinese sturgeon; growth hormone receptor; growth hormone binding protein; ligand binding

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Received: September 3, 2004 Accepted: October 28, 2004

This work was supported by a grant from the National and Natural Science Foundation of China (No. 30460036)

*Corresponding author: Tel, 86-21-54921283; Fax 86-21-54921011; E-mail, [email protected]