An example of structural determination by cryo-tomography and STA within FIB-milled Chlamydomonas reinhardtii cell [14 ]. The left and top right panels show a greyscale slice through a FIB-milled tomogram with ER membranes rendered in solid beige. The 19.4 Å subtomogram average of the ER-associated ribosome (EMDB 4145, bottom right panel: large ribosome subunit, orange; small subunit, blue; membrane, beige) is back-plotted according to aligned positions and orientations, demonstrating the in situ arrangement of ER-associated ribosomes. The resolution was sufficient for the authors to deduce the domain organisation of this complex. Raw tomogram and ribosome co-ordinates courtesy of Stefan Pfeffer and Friedrich Förster.