Fig. 3
From: The signalling conformation of the insulin receptor ectodomain
Detail of the cryo-EM structure of IRΔβ-zipInsFv. a Interaction of insulin with FnIII-1′, showing in particular the interaction of IR Arg539′ with insulin HisB10 (boxed residue labels). The dashed green line represents the poorly ordered segment between residues Ser541′ and Ser545′. b N-terminal region of the αCT′ helix showing termination of the helix at Asp689′ and the formation of a possible salt bridge between Lys687′ and Glu695′, as well as a possible conformation for the Cys 682′:Cys683′:Cys685′ triplet. Density shown is from the upper map. The green circle indicates the effective location of the four-glycine insert in the 686G4 mutant receptor and receptor ectodomain (see main text). c Density extracted from the lower map in the vicinity of the insulin-free domain L1, showing the density feature on the central β sheet of the domain (circled) and the overhanging CR′ domain loop containing residues Lys267′ to Gly273′ (dashed red line). The relative location of the αCT helix in the crystal structure of apo IRΔβ is shown for reference and is not included in the atomic model of IRΔβ-zipInsFv. d Density features (circled) associated with the unmodelled and partially disordered segments of ID and ID′. Density shown is extracted from both the upper and lower maps (as indicated on the right of the panel)
