IGFBP-1

The insulin-like growth factor binding protein (IGFBP) family is a critical component of the insulin-like growth factor (IGF) system that acts as transport proteins, prolongs half-life of IGFs, regulates the clearance of the IGFs, provides a tissue specific localization, and directly modulates IGFs' actions. The IGFBPs comprise a superfamily of six proteins (IGFBP-1-6) that bind to IGFs with high affinity and specificity and a family of IGFBP-related proteins (IGFBP-rPs, since IGFBP-7 to -10), which are structurally similar to the IGFBPs but bind IGFs with much lower affinity. In addition, the effects of IGFBPs on IGFs are regulated in part by IGFBP proteases. Thus, as far as IGF action is concerned, IGFBP proteases may also be regarded as part of the IGF family because they indirectly regulate the action of IGFs