open access

https://hdl.handle.net/2115/38999

Salmon serum 22 kDa insulin-like growth factor-binding protein (IGFBP) is IGFBP-1

Cloning of salmon IGFBP-1

英語

cloning

2005-01

Society for Endocrinology

Journal of Endocrinology

184(1)

267-276

Western ligand blotting of salmon serum typically reveals three insulin-like growth factor binding proteins (IGFBPs) at 22, 28 and 41 kDa. Physiological regulation of the 22-kDa IGFBP is similar to that of mammalian IGFBP-1; it is increased under catabolic states such as fasting and stress. On the other hand, its molecular weight on Western ligand blotting is closest to mammalian IGFBP-4. The conflict between physiology and molecular weight makes it difficult to conclude the identity of the 22-kDa IGFBP. This study therefore aimed to identify the 22-kDa IGFBP based on protein and cDNA sequences. The 22-kDa IGFBP was purified from Chinook salmon serum by a combination of IGF-affinity chromatography and reverse-phase chromatography. N-terminal amino acid sequence of the purified protein was used to design degenerate primers. Degenerate polymerase chain reaction (PCR) with liver template amplified a partial IGFBP cDNA, and full length cDNA was obtained by 5'- and 3'-rapid amplification of cDNA ends (RACE). The 1915-bp cDNA clone encodes a 23.8 kDa IGFBP and its N-terminal amino acid sequence matched that of purified 22-kDa IGFBP. Sequence comparison with six human IGFBPs revealed that it is most similar to IGFBP-1 (40% identity and 55% similarity). These findings indicate that salmon 22-kDa IGFBP is IGFBP-1. Salmon IGFBP-1 mRNA is predominantly expressed in the liver and its expression levels appear to reflect circulating levels. The 3'-untranslated region of salmon IGFBP-1 mRNA contains four repeats of the nucleotide sequence ATTTA, which is involved in selective mRNA degradation. In contrast, amino acid sequence analysis revealed that salmon IGFBP-1 does not have an Arg-Gly-Asp (RGD) integrin recognition sequence nor a Pro, Glu, Ser and Thr (PEST) rich domain (a segment involved in rapid turnover of protein), both of which are characteristics of mammalian IGFBP-1. These findings suggest that association with the cell surface and turnover rate may differ between salmon and mammalian IGFBP-1.

学術雑誌論文

Accepted Manuscript

Disclaimer. This is not the definitive version of record of this article. This manuscript has been accepted for publication in Journal of Endocrinology, but the version presented here has not yet been copy edited, formatted or proofed. Consequently, the Society for Endocrinology accepts no responsibility for any errors or omissions it may contain. The definitive version is now freely available at http://dx.doi.org/10.1677/joe.1.05880 © 2005 Society for Endocrinology.

0022-0795

1479-6805

AA00697140