Fig. 3: Cryo-EM structure of the IRIns+A43 complex.
From: Functional selectivity of insulin receptor revealed by aptamer-trapped receptor structures
a Half-turn views of the IRA43+Ins structure. Each protomer of a dimer is colored green or orange. The A43 aptamer is colored cyan and the insulin is colored magenta. b Close-up view of the αCT-αCT′ crosslinked bridge between insert domains (blue box in Fig. 3a). c Close-up view of the A43 binding site located at the CR, L2, and FnIII-1′ domains (red box in Fig. 3a). d Cartoon representation of the A43 structure. Labels for the 2′-deoxy-ribose sugar (d) are omitted for clarity. The A43-interacting residues are shown in the same scheme as in Fig. 2b. e Overall structure of the A43 aptamer. f Structure of insulin binding to FnIII-1′ (top left, PBD: 6PXV)27. Structure of A62 binding to FnIII-1′ from the IR2xA62 complex (top right). Structure of A43 binding to FnIII-1′ from the IRA43+Ins complex (bottom left). g Cartoon representation of a model for the positive cooperativity of aptamers with insulin binding. h Structural comparison of IRA62+Ins (left) and IRA43+Ins (right) shown in surface representation. A62 and A43 are colored violet and cyan, respectively.
