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Transferrin is an insulin-like growth factor-binding protein-3 binding protein
S A Weinzimer1, T B Gibson, P F Collett-Solberg
1Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
The Journal of Clinical Endocrinology and Metabolism
|April 12, 2001
Summary
Transferrin (Tf) specifically binds Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3), impacting cell growth and apoptosis. This novel interaction reveals a new mechanism for IGFBP-3
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) mediates cellular effects independent of IGF action.
- These effects are mediated by specific binding proteins/receptors located in various cellular compartments and the extracellular matrix.
Purpose of the Study:
- To identify and characterize novel binding proteins for IGFBP-3.
- To investigate the functional consequences of the interaction between IGFBP-3 and its binding partners.
Main Methods:
- Human serum fractionation using an IGFBP-3 affinity column.
- Protein identification via sequencing, database searching, and Western immunoblotting.
- Biosensor interaction analysis and yeast two-hybrid system for interaction confirmation.
Main Results:
- Transferrin (Tf) was identified as a specific binding protein for IGFBP-3, with holo-Tf showing higher affinity.
- Interaction analysis confirmed a specific, sensitive binding between Tf and IGFBP-3, potentially near the nuclear localization site.
- Tf treatment modulated IGFBP-3-induced cell proliferation and apoptosis in distinct cell types.
Conclusions:
- Transferrin (Tf) specifically binds to Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3).
- This Tf-IGFBP-3 interaction influences key cellular processes, including proliferation and apoptosis.
- The findings reveal a novel physiological role for Tf in mediating IGFBP-3's cellular functions.