SEQUENCE COMPARISON AND PREDICTED STRUCTURE FOR THE 4 EXON-ENCODED REGIONS OF HUMAN INSULIN-LIKE GROWTH-FACTOR BINDING-PROTEIN-4

The IGFBPs bind to and modulate the function of the IGFs in various wa ys. Human IGFBP-4 inhibits IGF mediated cell proliferation. The IGFBP exon-encoded regions were aligned and secondary structure predictions for hICFBP-4 were developed yielding predicted 3D co-ordinates for eac h such region of hIGEBP-4. The exon 1 encoded region is the most conse rved among the IGFBPs. That of hIGFBP-4 is predicted as an array of be ta-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 m ostly an amphipathic helix. The remaining regions are also conserved a mong the IGFBPs. Those of hIGFBP-4 are also predicted to contain helic es. The predicted structure of hIGFBP-4 comprises amino terminal beta- strands with four helices in the carboxy terminal two thirds of the mo lecule.