A modified neurophysin, des 1-6 bovine neurophysin II, has been crysta
llized in the absence of bound hormone or hormone analogue. These crys
tals represent the first crystals of ligand-free neurophysin, and are
essential for understanding neurophysin-hormone recognition as well as
hormone-induced neurophysin dimerization. The crystals diffract to be
yond 1.8 Angstrom resolution, belong to space group P3(1)21 (or P3(2)2
1) with n = 48.85, c = 78.61 Angstrom, and contain one molecule per as
ymmetric unit.