Cross-species comparison of mIIb with hIIb and rIIb. The single-letter amino acid sequence of mIIb is shown at the top and those of the other 2 species are shown below. A”:” refers to an identical homologous aa. A “–” refers to a missing aa. The start site for mature IIb is indicated by an arrow. The 3 regions of the N-terminal β-propeller regions discussed are grayed in and labeled. The transmembrane domain is crosshatched grayed in and is also labeled. The double-arginine cleavage site is underlined.