INSULIN-LIKE GROWTH FACTOR-BINDING PROTEINS (IGFBPS) AND THEIR REGULATORY DYNAMICS

The IGFBPs are a family of homologous proteins that have co-evolved wi th the IGFs and that confer upon the IGF regulatory system both functi onal and tissue specificity. IGFBPs are not merely carrier proteins fo r IGFs, but hold a central position in IGF ligand-receptor interaction s through influences on both the bioavailability and distribution of I GFs in the extracellular environment. In addition, IGFBPs appear to ha ve intrinsic biological activity independent of IGFs. The current stat us of research on IGFBPs is reviewed herein. Following a brief introdu ction to the entire IGF/IGFBP system, separate sections for each of th e six cloned mammalian IGFBPs, the most extensive for IGFBP3, cover se lected topics that emphasize the dynamics of IGFBPs-that is, their reg ulation in cells, their functionally important post-translational modi fications, and their interactions in the cellular microenvironment-and how these dynamics influence physiological function. (C) 1996 Elsevie r Science Ltd