Insulin-like growth factor binding proteins (IGFBPs) are known to be important modulators of the insulin-like growth factor (IGF-I). However, their precise role is as yet unclear. Further, recent studies have indicated that IGFBP-3 has a receptor mediated growth inhibitory response of its own. In the present study, we quantified the binding characteristics of IGFBP-3 to bovine aortic endothelial (BAE) cells. Binding studies at 4 <sup>o</sup>C were conducted and a specific binding curve for IGFBP-3 was obtained. IGFBP-3 was found to bind with an equilibrium dissociation constant (K<sub>D</sub>) value of 3.1 x 10<sup>-10</sup> M. The role of heparan sulfate proteoglycans (HSPG) in the IGFBP-3 binding mechanism was also examined. It was seen that inactivation of the cell surface HSPGs with 75 mM sodium chlorate did not affect IGFBP-3 binding. Further, there have been reports of inhibition of IGFBP-3 binding by heparin in the media. Hence, the most probable interaction of HSPG with IGFBP-3 occurs in the extracellular region, with soluble HSPGs acting as receptors for IGFBP-3 and decreasing the net cell associated ligand receptor interaction. This is likely, since IGFBP-3 is known to possess a heparin binding domain. Simultaneous introduction of IGF-I and IGFBP-3 into the extracellular media decreased IGFBP-3 binding to the cell surface, which might imply that IGF-I and IGFBP-3 regulate each other's action. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/36928 |
| Date | 24 August 1998 |
| Creators | Parghi, Nirav |
| Contributors | Chemical Engineering, Forsten-Williams, Kimberly, Conger, William L., Akers, Robert Michael |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | thesisfinA.PDF |
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