a, The four large intrinsic subunits of the spinach PSII core superposed on the corresponding subunits of the TvPSII core. The protein backbones and cofactors are shown as ribbon and stick models, respectively. Silver, spinach PSII core subunits; green, TvPSII core subunits. b, The locations of 12 low-molecular-mass intrinsic subunits in the spinach PSII–LHCII supercomplex. These subunits are coloured and the rest of the supercomplex is grey. c, The densities for the low-molecular-mass intrinsic subunits are shown as blue meshes. The corresponding models are shown as cyan sticks.