The structure of kistrin, which is a member of a homologous family of
glycoprotein IIb-IIIa (GP IIb-IIIa) antagonists and potent protein inhibitors of
platelet aggregation, has been determined by two-dimensional nuclear magnetic
resonance (NMR) spectroscopy. The 68-residue protein consists of a series of
tightly packed loops held together by six disulfide bonds and has almost no
regular secondary structure. Kistrin has an Arg-Gly-Asp (RGD) adhesion site
recognition sequence important for binding to GP IIb-IIIa that is located at the
apex of a long loop across the surface of the protein.
