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. 2023 Oct 9;24(19):15006. doi: 10.3390/ijms241915006

Figure 2.

Figure 2

Structure of IR receptors. (A) Illustration showing different IR domains encoded by the 22 exons. IR has two main subunits: α and β. The α subunit contains 5 main domains, L1 (AA 28–174) CR (AA 182–339), and L2 (AA 340–497), and 2 Fibronectin subunits: FnIII-1 (residue 624–726) and FnIII-2 (757–842). The two α-subunits are linked by a disulfide bond between the two Cys 524 in the first FnIII domain. One to three of the triplet Cys at 682, 683, and 685 in the insert within the second FnIII domain are also involved in α-α disulfide bridges. There is a single disulfide bridge between α and β subunits between Cys 647 in the insert domain and Cys 872. The β subunit details are explained in the main text. Teal arrow shows 6 O-glycosylations, whereas the pink arrows imply the N-glycosylation. (B) IR-B amino acid sequence colored to identify each domain sequence presented in (A). (C) 3D structure of IR-B showing the Λ-shaped structure when no ligand is bound to it. (D) Structural differences between IR-A and IR-B. JM: Juxtamembrane, TK: Tyrosine Kinase. The 3D models were created using Swiss Model.