A model for the structure of a homodimeric prohormone: the precursor to the locust neuropeptide AKH I.

We have determined the structure in solution of a homodimeric protein that is a precursor to the locust neuropeptide adipokinetic hormone I using nuclear magnetic resonance spectroscopy. This precursor, called P1, is comprised of two 41 residue strands joined by a single inter-chain disulphide at Cys39. We have also determined the structure of an end product of P1 processing, called APRP1; this is a homodimer comprised of residues 14-41 of P1. Nuclear Overhauser Effect (nOe) data indicate that in both P1 and APRP1, residues 22-37 (numbered with respect to P1) form pairs of alpha-helices, with no evidence for any other secondary structure.