Extended Data Fig. 1. Subunit organisation of FluPol_A heterotrimers.

a, b, Views of the structure of human H3N2 (a) and avian H5N1 (b) FluPol_A heterotrimers, coloured according to subunit. c–e, Structures of human H3N2 FluPol_A subunits PA (c), PB1 (d) and PB2 (e), coloured and labelled by domain. f, Domain maps of each H3N2 FluPol_A subunit. g-i, The 2D Fo – mFc electron density maps of FluPol_A dimer interface as shown in Fig. 1c (g, stereo view), and 1d (h, stereo view), as well as of the complete FluPol_A dimer (i), are shown in gray mesh (contoured at 1.5 σ, all from the H3N2 FluPol_A structure model).