Recombinant Human IGFBP-1 Protein, CF

The superfamily of insulin-like growth factor (IGF) binding proteins include the six high-affinity IGF binding proteins (IGFBP) and at least four additional low-affinity binding proteins referred to as IGFBP related proteins (IGFBP-rP). All IGFBP superfamily members are cysteine-rich proteins with conserved cysteine residues, which are clustered in the amino- and carboxy-terminal thirds of the molecule. IGFBPs modulate the biological activities of IGF proteins. Some IGFBPs may also have intrinsic bioactivity that is independent of their ability to bind IGF proteins. Post-transitional modifications of IGFBP, including glycosylation, phosphorylation and proteolysis, have been shown to modify the affinities of the binding proteins to IGF.

Human IGFBP-1 cDNA encodes a 259 amino acid (aa) residue precursor protein with a putative 25 aa residue signal peptide that is processed to generate the 234 aa residue mature protein. IGFBP-1 contains an integrin receptor recognition sequence (RGD sequence) but lacks potential N-linked glycosylation sites. IGFBP-1 is expressed in liver, decidua, kidneys and is the most abundant IGFBP in amniotic fluid. Serum levels of IGFBP-1 are lowest after meals. Hepatocyte production of IGFBP-1 is regulated at the transcriptional level due to the affects of insulin and corticosteriods. IGFBP-1 binds equally well to IGF-I and IGF-II, with phosphorylated forms of IGFBP-1 exhibiting higher binding affinities.