Evolution of the insulin superfamily: cloning of a hybrid insulin/insulin-like growth factor cDNA from amphioxus.
AUTOR(ES)
Chan, S J
RESUMO
Although insulin and the insulin-like growth factors (IGFs) share marked similarities in amino acid sequence and biological activity, their evolutionary origins have not been resolved. To investigate this issue, we recently cloned a cDNA encoding an insulin-like peptide (ILP) from a primitive chordate species, amphioxus (Branchiostoma californiensis). The deduced sequence of amphioxus preproILP indicates that it is a hybrid molecule containing features characteristic of both insulin and IGF. Like proinsulin, amphioxus proILP contains a C-peptide, which is flanked by paired basic residues and is probably removed by proteolysis. However, proILP also contains an extended carboxyl-terminal peptide region that can be divided into D and E domains similar to those of proIGF. Sequence comparisons show that the amphioxus ILP A and B domains are equally homologous to those of human insulin and IGF-I and -II. Based on these results and the exon-intron organization of the amphioxus ILP gene, we propose that IGF emerged at a very early stage in vertebrate evolution from an ancestral insulin-type gene.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=55156Documentos Relacionados
- Transdominant inhibition of tyrosine kinase activity in mutant insulin/insulin-like growth factor I hybrid receptors.
- Increased expression of insulin/insulin-like growth factor-I hybrid receptors in skeletal muscle of noninsulin-dependent diabetes mellitus subjects.
- Evolution of the vasopressin/oxytocin superfamily: characterization of a cDNA encoding a vasopressin-related precursor, preproconopressin, from the mollusc Lymnaea stagnalis.
- Cloning, sequence analysis and expression of a cDNA encoding a novel insulin-like growth factor binding protein (IGFBP-2).
- Nucleotide sequence of a porcine insulin-like growth factor II cDNA.