REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Mouse monoclonal antibody 24-60 (anti-human IGF-1R)	(Soos et al., 1992)	N/A
Mouse monoclonal antibody 83-7 (anti-human IR)	(Soos et al., 1986)	N/A
Mouse monoclonal antibody 18-44 (anti-human IR)	(Soos et al., 1986)	N/A
Mouse monoclonal antibody 9E10 (anti-c-myc)	CSIRO Laboratories, Parkville, Australia	ATCC CRL1729
IRDye 800CW Goat anti-mouse IgG	LI-COR Biosciences	Cat# 926-32210; RRID: AB_621842
Chemicals, peptides, and recombinant proteins
9E10 c-myc epitope peptide, sequence EQKLISEEDL (>75% purity)	Genscript	N/A
18-44 IR epitope peptide, sequence TSPEEHRPFE (>70% purity)	Genscript	N/A
Receptor grade IGF-I	GroPep	Cat# CM001
IGF-I	(King et al., 1992)	N/A
Eu-IGF-I	(Denley et al., 2004)	N/A
Insulin	Novo Nordisk	Actrapid
Fetal calf serum	Scientifix	FBSFR-62147A
G418	ThermoFisher Scientific	10131035
Puromycin	ThermoFisher Scientific	A1113802
L-Methionine sulfoximine	Merck	GSS-1015-F
Eu-N1-ITC chelate	Perkin Elmer	1244-302
DELFIA Enhancement Solution	Perkin Elmer	1244-104
Fetal Bovine Serum, dialyzed	ThermoFisher Scientific	30067344
DMEM with Glucose, without L-Glutamine	Lonza	12-614F
GS Supplement	Merck	GSS-1016-C
Trypsin Gold	Promega	Cat# V5280
FuGENE HD transfection agent	Promega	E2311
ProSep-vA resin	Millipore
Deposited data
Crystal structure of apo IGF-1R ectodomain	(Xu et al., 2018)	PDB: 5U8R
Crystal structure of apo IR ectodomain	(Croll et al., 2016)	PDB: 4ZXB
CryoEM structure of IGF-II bound IGF-1R (head region; open conformation	(Xu et al., 2020)	PDB: 6VXG
Model: IGF-I-bound HybZip, head region	This study	PDB: 7S0Q
Model: IGF-I-bound HybZip, leg region	This study	PDB: 7S8V
Map: IGF-I-bound HybZip, head region	This study	EMD-24791
Map: IGF-I-bound HybZip, leg region	This study	EMD-24927
Experimental models: Cell lines
BALB/c3T3 cells overexpressing IGF-IR	(Pietrzkowski et al., 1992)	P6
IGF-IR null mouse fibroblasts overexpressing the human IR-B	In-house; (Denley et al., 2004)	R-IR-B
CHO-Lec8	ATCC	ATCC CRL-1737
Recombinant DNA
IGF-1Rzip	(Xu et al., 2020)	N/A
IR-Bzip, custom synthesis and cloning	Genscript	N/A
pEE14 vector	Lonza	N/A
pJ509 vector	DNA 2.0	N/A
oligo 5'-GCGCGTCGACGCCT CCTTCAAGTCCCAG-3'	Integrated DNA Technologies	N/A
oligo 5'-GCGCTCTAGATTATT AATTCAGATCCTC-3'	Integrated DNA Technologies	N/A
Software and algorithms
RELION v3.0.5	(Nakane et al., 2018)	https://www3.mrc-lmb.cam.ac.uk/relion
CryoSPARC v2.11	(Punjani et al., 2017)	https://cryosparc.com/
ISOLDE v1.03b	(Croll, 2018)	https://isolde.cimr.cam.ac.uk/
Phenix v1.16-3549-000	(Afonine et al., 2018)	https://www.phenix-online.org/
Coot v0.8.9.1	(Emsley et al., 2010)	https://www2.mrc-lmb.cam.ac.uk/personal/pemsley/coot/
Chimera v1.11.2	(Pettersen et al., 2004)	https://www.cgl.ucsf.edu/chimera/
ChimeraX v0.91	(Goddard et al., 2018)	https://www.cgl.ucsf.edu/chimerax/
Graphpad Prism v9.0.0	Graphpad Software	https://www.graphpad.com/scientific-software/prism/
Other
Mini-Leak low divinylsulphone-activated resin	Kem-en-Tec	Cat# 1011 H
Sepharose CL-4B resin	GE Healthcare Lifesciences	Cat# 17015001
Sephadex-G75	GE Healthcare / Cytiva	Cat# 17005001
Pellicon 3 0.11 m2 10 kDa Ultracel concentrator	Merck-Millipore	Cat# P3C010C01
Superdex 200 Increase 10/300 GL	GE Healthcare Lifesciences	Cat# 28990944
0.5 mL 10 kDa Amicon Ultra concentrator	Sigma-Aldrich	Cat# UFC501008
UltrAuFoil R1.2/1.3 300-mesh grids	Quantifoil	N/A
Pelco easiGlow	Ted Pella	Cat# 91000S-230
Vitrobot mark IV	ThermoFisher Scientific	N/A