Identification of a second insulin-like growth factor in a fish species

Michael J. Shamblott, Thomas T. Chen

Research output: Contribution to journalArticle

Abstract

An internal portion of insulin-like growth factor (IGF) amplified from the total cDNA of rainbow trout (Oncorhynchus mykiss) liver by a PCR was used to screen a rainbow trout liver cDNA library, and recombinant clones encoding two distinct IGFs were isolated. On the basis of a 98.7% nucleotide and 98.3% predicted amino acid identity to coho salmon IGF-I, one cDNA sequence was identified as rainbow trout preproinsulin-like growth factor I (rtIGF-I). The second cDNA sequence shared 46.1% and 43.3% identity with rtIGF-I at the nucleotide and predicted amino acid levels, respectively, and was identified as rainbow trout preproinsulin-like growth factor II (rtIGF-II). Predicted amino acid sequence comparisons of rtIGFs with those of human IGFs indicate that rtIGF-I is more similar to human IGF-I than to human IGF-II, and that rtIGF-II is more similar to human IGF-II than to human IGF-I. Southern blot analysis of rainbow trout genomic DNA probed with rtIGF-I and -II cDNA suggests that these two forms of IGF originate from separate genes. The presence of a teleost IGF-II suggests that the divergence of IGFs occurred early in vertebrate evolution.

Original languageEnglish (US)
Pages (from-to)8913-8917
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume89
Issue number19
DOIs
StatePublished - Oct 1 1992

Keywords

  • DNA sequence
  • PCR
  • Teleost

ASJC Scopus subject areas

  • General

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