Regular Article
Single-Molecule Imaging of Human Insulin Receptor Ectodomain and Its Fab Complexes,☆☆

https://doi.org/10.1006/jsbi.1998.4066Get rights and content

Abstract

The insulin receptor (IR) is a four-chain, transmembrane dimer held together by disulfide bonds. To gain information about the molecular envelope and the organization of its domains, single-molecule images of the IR ectodomain and its complexes with three Fabs have been analyzed by electron microscopy. The data indicate that the IR ectodomain resembles a U-shaped prism of approximate dimensions 90 × 80 × 120 Å. The width of the cleft (assumed membrane-distal) between the two side arms is sufficient to accommodate ligand. Fab 83-7, which recognizes the cys-rich region of IR, bound halfway up one end of each side arm in a diametrically opposite manner, indicating a twofold axis of symmetry normal to the membrane surface. Fabs 83-14 and 18-44, which have been mapped respectively to the first fibronectin type III domain (residues 469–592) and residues 765–770 in the insert domain, bound near the base of the prism at opposite corners. These images, together with the data from the recently determined 3D structure of the first three domains of the insulin-like growth factor type I receptor, suggest that the IR dimer is organized into two layers with the L1/cys-rich/L2 domains occupying the upper (membrane distal) region of the U-shaped prism and the fibronectin type III domains and the insert domains located predominantly in the membrane-proximal region.

References (34)

  • E.M. Schaefer et al.

    Structural organization of the human insulin receptor ectodomain

    J. Biol. Chem.

    (1992)
  • L. Schaffer et al.

    Identification of a disulfide bridge connecting the α-subunits of the extracellular domain of the insulin receptor

    Biochem. Biophys. Res. Commun.

    (1992)
  • L.G. Sparrow et al.

    The disulphide bonds in the C-terminal domains of the human insulin receptor ectodomain

    J. Biol. Chem.

    (1997)
  • P.A. Tulloch et al.

    Electron and X-ray diffraction studies of influenza neuraminidase complexed with monoclonal antibodies

    J. Mol. Biol.

    (1986)
  • K. Christiansen et al.

    A model for the quaternary structure of human placental insulin receptor deduced from electron microscopy

    Proc. Natl. Acad. Sci. USA

    (1991)
  • Current Protocols in Immunology

    (1993)
  • Cited by (37)

    • Receptor tyrosine kinases (RTKs): from biology to pathophysiology

      2023, Receptor Tyrosine Kinases in Neurodegenerative and Psychiatric Disorders
    • Visualization of Ligand-Bound Ectodomain Assembly in the Full-Length Human IGF-1 Receptor by Cryo-EM Single-Particle Analysis

      2020, Structure
      Citation Excerpt :

      In the IGF-1R/insulin complex, the two (αβ) protomers assembled in a way that was different compared with the previously reported X-ray or cryo-EM IGF-1R/IR apo or complex structures (Croll et al., 2016; Menting et al., 2013; Scapin et al., 2018; Uchikawa et al., 2019; Weis et al., 2018; Xu et al., 2018). The insulin-bound protomer A interacted extensively with the insulin-free protomer B via L2, L2′, FnIII-1, FnIII-1′, FnIII-2, α-CT1 helix, and insulin, but the FnIII-3′ in protomer B was more flexible than that in protomer A and was partially disordered and was different from the well-recognized Λ-shaped model in the apo-IR or IGF-1R structures; this might be caused by insulin binding (Tulloch et al., 1999; Xu et al., 2018). In the previous Λ-shaped model, two (αβ) protomers interacted extensively, and each of the L1 domains interacted with FnIII-2 in the second (αβ) protomer.

    • Structural Congruency of Ligand Binding to the Insulin and Insulin/Type 1 Insulin-like Growth Factor Hybrid Receptors

      2015, Structure
      Citation Excerpt :

      In the case of the IR homodimer, these domains arrange in a two-fold symmetric, disulfide-linked Λ-shaped conformation (McKern et al., 2006; Smith et al., 2010; Tulloch et al., 1999) (Figure 1A). The ectodomain of IGF-1R likely exhibits a similar conformation (Tulloch et al., 1999; Whitten et al., 2009). Of fundamental importance to ligand binding is the C-terminal region (αCT) of the receptor α chain (Kurose et al., 1994), which in the case of IR has been shown to assemble in a predominantly α-helical conformation on the central β-sheet (L1-β2) of the L1 domain of the opposite monomer (Smith et al., 2010).

    View all citing articles on Scopus

    Peter Tulloch passed away on June 14, 1998.

    ☆☆

    Coligan, J. E.Kruisbeek, A. M.Margulies, D. H.Shevach, E. M.Strober, W.

    1

    To whom correspondence should be addressed. Fax: 61 3 9662 7101. E-mail:[email protected]

    View full text