Sequence Comparison and Predicted Structure for the Four Exon-Encoded Regions of Human Insulin-Like Growth Factor Binding Protein 4

Abstract

The IGFBPs bind to and modulate the function of the IGFs in various ways. Human IGFBP-4 inhibits IGF mediated cell proliferation. The IGFBP exon-encoded regions were aligned and secondary structure predictions for hIGFBP-4 were developed yielding predicted 3D co-ordinates for each such region of hIGFBP-4. The exon 1 encoded region is the most conserved among the IGFBPs. That of hIGFBP-4 is predicted as an array of β-strands that include the glycine and cysteine rich IGFBP concensus pattern and that terminate with a helix. The exon 2 encoded region is the most variable among the IGFBPs. That of hIGFBP-4 is predicted as mostly an amphipathic helix. The remaining regions are also conserved among the IGFBPs. Those of hIGFBP-4 are also predicted to contain helices. The predicted structure of hIGFBP-4 comprises amino terminal β-strands with four helices in the carboxy terminal two thirds of the molecule.

Key Words:

• IGFBP
• gene structure
• exons
• protein structure prediction