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Updated: Jul 12, 2026
08:58
Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques
Published on: July 5, 2018
Structure-function relationships of insulin-like growth factor binding protein 6 (IGFBP-6) and its chimeras
1Department of Internal Medicine, Veterans Administration Medical Center, Iowa City, IA 52246, USA.
Summary
Insulin-like growth factor binding protein 6 (IGFBP-6) chimeras show reduced endothelial cell binding and transport compared to IGFBP-3. These findings highlight differences in IGFBP interactions with endothelial cells.
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Biology
Background:
- Insulin-like growth factor binding proteins (IGFBPs) modulate IGF bioavailability and signaling.
- IGFBP-6 preferentially binds IGF-II, while IGFBP-3 interacts with both IGF-I and IGF-II.
- Endothelial cell interactions are crucial for IGFBP transport and function.
Purpose of the Study:
- To investigate the endothelial cell binding and transendothelial transport of IGFBP-6/IGFBP-3 chimeras.
- To compare the behavior of IGFBP-6/IGFBP-3 chimeras with IGFBP-4/IGFBP-3 chimeras.
- To elucidate the structural determinants of IGFBP interactions with endothelial cells.
Main Methods:
- Construction of IGFBP-6/IGFBP-3 chimeras (IGFBP-6(3), IGFBP-6(3)A, IGFBP-6(3)B) involving exchange of specific protein regions.
- Assessment of radiolabeled chimera binding to endothelial cells in vitro.
- Measurement of transendothelial transport of IGFBPs in a perfused heart model.
Main Results:
- IGFBP-6(3) did not bind to endothelial cells, unlike IGFBP-3.
- Double mutants (IGFBP-6(3)A, IGFBP-6(3)B) also failed to bind endothelial cells but competed with IGFBP-3 binding.
- Transendothelial transport of IGFBP-6 and IGFBP-6(3) in the perfused heart was significantly lower (25%) than that of IGFBP-3.
Conclusions:
- IGFBP-6/IGFBP-3 chimeras exhibit distinct endothelial cell binding properties compared to IGFBP-4/IGFBP-3 chimeras.
- Specific regions of IGFBPs dictate their interaction with endothelial cells.
- The capacity for transendothelial transport is significantly influenced by IGFBP structure and endothelial cell interactions.
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