Human IGFBP-4

Human Insulin-like growth factor binding protein-4 (IGFBP-4) is a 237 amino acid protein which is a member of a family of six circulating proteins that bind IGF-I and IGF-II with high affinity and modulate their metabolic and mitogenic effects. Human IGFBP-4 is present in biological fluids as an N-linked glycosylated form (28 kDa) and a non-glycosylated form. IGFBP-4 is primarily an inhibitor of IGF action and does not generally bind to cell surfaces.