Insulin-like Growth Factor-binding Protein 3 (IGFBP-3)

Insulin-like growth factors (IGF-1, IGF-II) are a family of peptides involved in the regulation of cell growth, the actions of which are mediated by binding to the insulin-like growth factor binding proteins. Six binding proteins (IGFBP-1 through IGFBP-6) have been described. IGFBP-3 is the most predominant of these. Approximately 95% of IGF-1 and IGF-II are bound to IGFBP-3, which makes this protein the major carrier of the insulin-like growth factors in circulation. The function of the binding protein is to extend the half-life of the growth factors in the circulation.