Identification of a family of low-affinity insulin-like growth factor binding proteins (IGFBPs): Characterization of connective tissue growth factor as a member of the IGFBP superfamily

摘要

The insulin-like growth factor (IGF) binding proteins (IGFBPs) modulate the actions of the insulin-like growth factors in endocrine, paracrine, and autocrine set- tings. Additionally, some IGFBPs appear to exhibit biological effects that are IGF independent. The six high-affinity IG- FBPs that have been characterized to date exhibit 40-60/100 amino acid sequence identity overall, with the most conserved sequences in their NH_2 and COOH termini. We have recently demonstrated that the product of the mac25/IGFBP-7 gene, which shows significant conservation in the NH2 terminus, including an "IGFBP motif" (GCGCCXXC), exhibits low- affinity IGF binding.