Insulin-like growth factor agonist molecules

A method for determining the amount in a biological fluid of IGFBP that binds a peptide comprising an amino acid sequence that is SEQ ID NO:

• 15 or SEQ ID NO:
• 16, which comprises:
• (a) contacting the fluid with
• 1) a first antibody attached to a solid-phase carrier, wherein the first antibody binds epitopes on the IGFBP such that in the presence of the antibody the IGF binding sites remain available on the IGFBP for binding to the peptide, thereby forming a complex between the first antibody and the IGFBP, and
• 2) a concentration of the peptide for a period of time sufficient to saturate all available IGF binding sites on the IGFBP, thereby forming a saturated complex;
• (b) removing the unbound peptide;
• (c) contacting the saturated complex with a detectably labeled second antibody which binds epitopes on the peptide which are available for binding when the peptide is bound to the IGFBP;
• (d) removing the unbound second antibody;
• and
• (e) quantitatively analyzing the amount of the labeled second antibody bound as a measure of the amount of IGFBP in the biological fluid.