Fig. 2.

Representative class averages of α_xβ₂ alone, α_xβ₂ with CBR LFA-1/2, and α_xβ₂ with CBR LFA-1/2 and MEM148 Fabs. (A) Class averages of α_xβ₂ alone. Most of the particles are in the bent conformation. (B) Class averages of the α_xβ₂–CBR LFA-1/2 complex. The particles mostly adopt extended conformations, in which the headpiece is closed with parallel legs (row 1), closed with crossed legs (row 2), or open (row 3). (C) Class averages of α_xβ₂ in complex with CBR LFA-1/2 and MEM148 Fabs. Approximately 70% of the particles are complexes with both Fabs, which adopt exclusively the extended-open headpiece conformation (row 1). The remaining 30% of particles are particles with only α_xβ₂–CBR LFA-1/2 Fab, which exhibit exactly the same conformational states (rows 2, 3, and 4), as seen in rows 1, 2, and 3, respectively, in B. To the right of each set of class averages, cartoons show the domain arrangement and Fab position. (Scale bar, 10 nm.)