Extended Data Table 3:

Cryo-EM data collection, refinement and validation statistics for N255A-hsPANX1^Hemi, N255A-hsPANX1^Gap, SMA-wt-hsPANX1.

	PANX1(N255A)Hemi (EMDB-21593) (PDB 6WBM)	PANX1 (N255A)Gap (EMDB-21594) (PDB 6WBN)	SMA–PANX1 (EMDB-21598)
Data collection and processing
Magnification	105,000	105,000	105,000
Voltage (kV)	300	300	300
Electron exposure (e−/Å2)	47.25	47.25	47.25
Defocus range (μm)	−1.2 – −1.8	−1.2 – −1.8	−1.2 – −1.8
Pixel size (Å)	0.812	0.812	0.812
Symmetry imposed	C7	C7	C7
Initial particle images (no.)	3,945,051	3,945,051	1,098,021
Final particle images (no.)	407,341	78,983	125,025
Map resolution (Å)	2.86	2.83	6.04
FSC threshold	0.143	0.143	0.143
Map resolution range (Å)	2.86 – 246.2	2.83 – 246.2	6.04 – 246.2
Refinement
Initial model used (PDB code)	De novo	De novo
Model resolution (Å)	3.10	3.12
FSC threshold	0.5	0.5
Model resolution range (Å)
Map sharpening B factor (Å2)	−119.822	−70.501
Model composition
Non-hydrogen atoms	19201	38402
Protein residues	2387	4774
Ligands	42	84
R.m.s. deviations
Bond lengths (Å)	0.006	0.01
Bond angles (°)	0.71	1.15
Validation
MolProbity score	2.03	1.88
Clashscore	13.68	11.23
Poor rotamers (%)	0.8	0.8
Ramachandran plot
Favored (%)	94.40	95.51
Allowed (%)	5.60	4.49
Disallowed (%)	0.00	0.00