Table 1.

Data processing and refinement statistics.

Data processing	Fce3–4 (1)	Fe3–4 (2)	Fce3–4 (3)	IgE-Fc
Structure name	P 1	P 21 “large”	P 21 “small”	IgE-Fc
No. of molecules in asymmetric unit	3	2	1	1
Space group	P 1	P 1 21 1	P 1 21 1	P 21 21 2
Unit cell dimensions (Å)	a = 47.67	a = 66.48	a = 46.53	a = 130.67
	b = 90.30	b = 100.36	b = 104.07	b = 75.78
	c = 92.91	c = 77.86	c = 52.94	c = 79.82
	a = 114.41°	ß = 97.35°	ß = 101.54°
	ß = 90.63°
	? = 96.10°
Resolution (Å): overall (outer shell)	81.61–2.20	100.36–2.00	51.87–2.26	79.82–1.75
	(2.25–2.20)	(2.05–2.00)	(2.33–2.26)	(1.80–1.75)
Completeness (%)a	98.9 (97.0)	100 (100)	99.9 (99.9)	99.9 (99.8)
Multiplicitya	5.7 (3.8)	14 (8.8)	4.1 (4.2)	13.1 (11.4)
Mean ((I)/s(I))a	7.5 (2.0)	14 (1.6)	5.9 (2.0)	14.0 (1.3)
Rmergea	0.13 (1.103)	0.291 (2.218)	0.130 (1.834)	0.098 (1.982)
Rpima	0.085 (0.899)	0.069 (1.143)	0.069 (1.000)	0.028 (0.607)
CC1/2a	0.997 (0.656)	0.995 (0.651)	0.993 (0.362)	0.999 (0.495)
Wilson B-factor (Å2)	43.66	32.92	46.51	25.10
Refinement	Fce3–4 (1)	Fe3–4 (2)	Fce3–4 (3)	IgE-Fc
Rwork/Rfree (%)b	21.34/23.36	20.24/22.60	20.15/23.56	19.73/23.23
No. of reflections	60,090	68,373	23,108	80,159
RMSD:
Bond lengths (Å)	0.003	0.003	0.006	0.009
Bond angles (°)	0.591	0.619	0.767	0.944
Coordinate error (Å)	0.27	0.25	0.30	0.27
No. of atoms:
Protein	8732	6358	2986	4933
Carbohydrate	346	263	122	144
Solvent	213	519	37	601
Other	73c	33d	50e	72f
Ramachandran plot:
Favoured (%)	98.09	98.28	97.42	98.00
Allowed (%)	99.82	100	100	100

^aValues in parentheses are for the highest resolution shell.

^bR_free set comprises 5% of reflections.

^cEthylene glycol, polyethylene glycol, phosphate.

^dEthylene glycol, polyethylene glycol.

^eEthylene glycol, polyethylene glycol, sulphate.

^fEthylene glycol, polyethylene glycol.