Table 1.

Summary of the available structures of IR.

Classification	Structure of IR	References
Domain layout	an (αβ)2 disulfide-linked homodimer	[35]
cDNA sequenced	α chain lies on the N-terminal of the β chain
3D structure of human apo IR ectodomain	intracellular unphosphorylated from TKD (2.1 Å resolution, PDB 1IRK)
	receptor’s isolated L1-CR-L2 module (2.32 Å resolution, PDB 2HR7)
	intact receptor ectodomain in apo form (3.8 Å resolution, PDB 2DTG)
CryoEM structures of IR	insulin holoreceptor (full-length receptor inclusive of transmembrane and cytoplasmic elements)	[42]
	isolated receptor ectodomain	[41,43]
	an ectodomain construct (leucine-zippered receptor ectodomain)	[44]