Turbot (Psetta maxima) IGF-I and receptor cDNAs cloning.

The IGFs, their receptors and their binding proteins constitute a family of cellular modulators that play essential functions in the regulation of gro wth and development. In our study, we have carried out the molecular charac terization of the IGF-I and its receptor (IGF-1R) from the turbot (Psetta m axima), a teleost flatfish. By RT-PCR, we have cloned an IGF-I cDNA. The deduced peptide shows 70-96% i dentity with the other vertebrate IGF-I sequences previously described. We have also cloned a cDNA encoding the IGF type 1 receptor precursor from an embryos cDNA library. The deduced IGF-IR primary sequence contains all the topological features characteristic of the IGF-1R. Indeed, the turbot recep tor is highly conserved compared to its mammalian counterparts, particularl y within the catalytic domain. Some differences were nevertheless observed in the primary sequence that may affect the function of the receptor. Final ly, by using an RT-PCR approach, we have shown that IGF-1R mRNA polyadenyla tion status varies according to the developmental stage.