Table 1.

Data collection and refinement statistics.

	MmIgG1 Fc	MmIgG2 Fc	MmIgG3 Fc	MmIgG4 Fc
Data collection Wavelength, Ǻ Space group Cell parameters a, b, c, Å α, β, γ, ° Complexes/a.u. Resolution, (Å) # of reflections Total Unique Rmergeb, % Rpim, % CC1/2 I/σ Completeness, % Redundancy	0.979 P21 57.6, 64.5, 80.6 90, 104.5, 90 1 50–2.8 (2.85–2.8) 40,046 13,809 16.6 (73.9) 11.3 (57.9) 0.99 (0.62) 9.7 (0.8) 95.2 (81.7) 2.9 (2.0)	0.979 P32 66.9, 66.9, 87.5 90, 90, 120 1 50–2.95 (3.0–2.95) 23,189 8,919 8.7 (65.7) 6.4 (48.5) 0.99 (0.75) 13.6 (1.29) 96.1 (97.7) 2.6 (2.7)	0.979 P32a 65.9, 65.9, 89.1 90, 90, 120 1 50–3.45 (3.5–3.45) 13,835 5,321 24.2 (80.2) 17.2 (57.0) 0.99 (0.30) 7.4 (1.3) 94.9 (98.0) 2.6 (2.6)	0.979 P32 66.6, 66.6, 90.7 90, 90, 120 1 50–3.25 (3.3–3.25) 35,792 7,018 9.0 (97.1) 4.4 (49.1) 0.99 (0.65) 31.3 (1.2) 98.9 (99.7) 5.1 (4.8)
Refinement statistics Resolution, Å Rc % Rfree, % chain A res. range chain B res. range # of atoms Protein Water Ligand/Ion Overall B value (Å)2 Protein Water Ligand/Ion RMSDd Bond lengths, Å Bond angles, ° Ramachandrane favored, % allowed, % outliers, % PDB ID	50.0–2.8 22.1 27.2 [236–444] [236–444] 3,331 7 199 77 51 112 0.006 1.1 90.1 5.8 4.1 6D4E	50.0–2.95 20.7 26.1 [237–445] [236–444] 3,337 6 198 76 52 95 0.008 1.2 95.7 3.1 1.2 6D4I	50.0–3.45 24.9 27.0 [237–444] [236–444] 3,320 – 198 108 – 103 0.006 1.0 73.6 20.6 5.8 6D4M	50.0–3.25 21.3 26.5 [237–444] [237–444] 3,310 – 198 151 – 151 0.008 1.3 89.8 9.0 1.2 6D4N

Values in parentheses are for highest-resolution shell.

^aTwinned crystal with a twin fraction of 0.308 and twin law of (h,-h-k,-l) as determined by Xtriage¹²

^b R_merge = ∑│I − <I>│/∑I, where I is the observed intensity and <I> is the average intensity obtained from multiple observations of symmetry-related reflections after rejections.

^c R = ∑║F_o│ − │ F_c║/∑│F_o│, where F_o and F_c are the observed and calculated structure factors, respectively.

^dRMSD = Root mean square deviation.

^eCalculated with MolProbity.