Solution structure of an insect growth factor, growth-blocking peptide

Growth-blocking peptide (GBP) is an insect growth factor consisting of 25 a mino acid residues that retards the development of lepidopteran larvae at h igh concentration while it stimulates larval growth at low concentration. I n this study, we determined the solution structure of GBP by two-dimensiona l H-1 NMR spectroscopy. The structure contains a short segment of double-st randed beta-sheet involving residues 11-13 and 19-21 and a type-II beta-tur n in the loop region (residues 8-11), whereas the N and C termini are disor dered. This is the first report of the three-dimensional structure of the p eptiderigic insect growth factor, and the structure of the well defined reg ion of GBP was found to share similarity with that of the C-terminal domain of the epidermal growth factor (EGF). Because GBP has been reported to sti mulate DNA synthesis of not only insect cells but also human keratinocyte c ells at the same level with EGF, the structural similarity between GBP and EGF may lead to the interaction of GBP to EGF receptor.