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

Abstract

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 M−1. 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.