Effect of an insulin-like growth factor binding protein fusion protein on thymidine incorporation in neuroblastoma and rhabdomyosarcoma cell lines.

A fusion protein, FP 6/3, composed of IGF binding protein (IGFBP)-6 and IGFBP-3 was synthesized where the complete sequences of each binding protein were fused together into a single chimeric protein. The orientation of this fusion protein's structure has the N terminus of IGFBP-3 fused to the C terminus of IGFBP-6, leaving the key binding areas of each open. FP 6/3 bound to cells via its IGFBP-3 component and retained the increased affinity for IGF-II via its IGFBP-6 component.

IGF-I and IGFBP-3 transport in the rat heart.

Specific binding of IGF-binding protein (IGFBP)-3 was shown to be present in the isolated, beating rat heart. The uptake of perfused (125)I-labeled IGF-I in the beating heart was decreased to 9% by blocking IGF-I binding sites with the IGF-I analog Long R(3) (LR(3)) IGF-I. When LR(3) was perfused with complexes of (125)I-IGF-I.