REAGENT or RESOURCE	SOURCE	IDENTIFIER
Chemicals, Peptides, and Recombinant Proteins
tris(2-carboxyethyl)phosphine (TCEP)	Pierce	Cat#20491
bis(2,2,5,5-tetramethyl-3-imidazoline-1-oxyl-4-il)-disulfide	Enzo	Cat# ALX-430-102-M010
Papain	Pierce	Cat#20341
HEPES	Thermo Fisher Scientific	Cat#15630080
MEM Non-Essential Amino Acid Solution (MEM NEAA)	Thermo Fisher Scientific	Cat#11140050
GlutaMAX Supplement	Thermo Fisher Scientific	Cat#35050061
Sodium Pyruvate	Thermo Fisher Scientific	Cat#11360070
Hygromycin B	Thermo Fisher Scientific	Cat#10687010
BG505 SOSIP.664 v3.2	(Sanders et al., 2013)	N/A
B41 SOSIP.664 v 4.2	(Pugach et al., 2015)	N/A
17b Fab	(Thali et al., 1993)	N/A
2G12 IgG	(Buchacher et al., 1994)	N/A
21c IgG	(West et al., 2010, Xiang et al., 2002)	N/A
sCD4	(Brighty et al., 1991)	N/A
b12 Fab	(Burton et al., 1991)	N/A
8ANC195 Fab	(Scharf et al., 2014)	N/A
Critical Commercial Assays
FreeStyle 293 Expression Medium	Thermo Fisher Scientific	Cat#12338018
ProCHO-5 serum-free medium	Sartorius	Cat#BE12-766Q
Deposited Data
BG505-sCD4-17b-8ANC195 cryo-EM map	EMDB	EMDB: 7516
BG505-sCD4-17b-8ANC195 coordinates	PDB	PDB: 6CM3
B41-sCD4-21c-8ANC195 cryo-EM map	EMDB	EMDB: 9038
B41-sCD4-21c-8ANC195 coordinates	PDB	PDB: 6EDU
Experimental Models: Cell Lines
HEK293-6E	National Research Council of Canada	Cat#11565
CHO Flp-In cells	Invitrogen	Cat# R75807
Recombinant DNA
pTT5 mammalian expression vector (used to express all BG505 SOSIP variants and all ligands)	National Research Council of Canada	N/A
Software and Algorithms
Pymol	Schrödinger LLC; https://www.schrodinger.com/pymol	RRID: SCR_000305
UCSF Chimera	(Pettersen et al., 2004)	RRID: SCR_004097
Phenix	(Adams et al., 2010)	RRID: SCR_014224
Coot	(Emsley and Cowtan, 2004)	RRID: SCR_014222
Relion	(Scheres, 2012)	RRID: SCR_016274
SerialEM	(Mastronarde, 2005)	http://bio3d.colorado.edu/SerialEM/
Rosetta	(Wang et al., 2016b)	RRID: SCR_015701
Other
HiLoad 16/600 Superdex 200 pg column	GE Healthcare	Cat#28989335
HiTrap Q HP, 5 mL column	GE Healthcare	Cat#17115401
Superose 6 10/300 GL column	GE Healthcare	Cat#17517201
2G12 5 ml column made in-house using using NHS-activated HP resin and 2G12 IgG	GE Healthcare	Cat#17071601
Protein A column	GE Healthcare	Cat#17040301
400 Mesh Quantifoil R1.2/1.3 copper grids	EM Resolutions	QR1213400Cu50
300 Mesh Quantifoil R1.2/1.3 gold grids	EM Resolutions	QR1213400Au50