title: Transferrin binds insulin-like growth factors and affects binding properties of insulin-like growth factor binding protein-3.
abstract: In the circulation, most of the insulin-like growth factors (IGFs) are bound to a ternary 150 kDa complex with IGF-binding protein (IGFBP)-3 and the acid labile subunit. In the current study, we identify transferrin (Tf) by mass spectrometry, and immunoprecipitation as a component of a major IGF-binding fraction separated from human plasma. IGF ligand blotting, cross-linkage experiments and surface plasmon resonance spectrometry have been used to demonstrate the capability of Tf to bind IGFs specifically. In combination with Tf, IGFBP-3 showed a 5-fold higher affinity for IGF-II than IGFBP-3 alone. The data suggest that Tf may play an important role in regulating IGF/IGFBP-3 functions.
authors.affiliation: Children's Hospital-Biochemistry, University of Hamburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Storch
authors.forename: B
authors.initials: B
authors.lastname: Kübler
authors.forename: S
authors.initials: S
authors.lastname: Höning
authors.forename: M
authors.initials: M
authors.lastname: Ackmann
authors.forename: J
authors.initials: J
authors.lastname: Zapf
authors.forename: W
authors.initials: W
authors.lastname: Blum
authors.forename: T
authors.initials: T
authors.lastname: Braulke
mesh_terms: D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D007700:Kinetics; D013058:Mass Spectrometry; D011233:Precipitin Tests; D011485:Protein Binding; D020349:Surface Plasmon Resonance; D014168:Transferrin / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015003:Yeasts
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D014168:Transferrin; D007335:Insulin-Like Growth Factor II