Table 1. Data parameters.

Data collection parameters			HP3	HP4
Instrument	X33 (EMBL, DORIS ring, DESY)
Beam geometry		2 mm×0.6 mm
Wavelength [Å]		1.5
range [Å−1]		0.0074-0.5
Exposure time [s]		8×15
Temperature [K]		283
Concentration range [mg/ml]		2.2–3.8
		0.7–1.2
Structural parameters
[% ] from P(r)		53±5		32.25±12
[Å ] from P(r)		31.2±1.2		18.8±0.1
[% ] from Guinier		72.8±9		31.6±0.06
[Å ] from Guinier		29.3±2		17.8±2.1
[Å] from data		117		61.4
[Å ]	Model 1	30		17.4
[Å ]	Model 2	33
[Å] of model envelope	Model 1	112		61.43
	Model 2	124
Porod volume estimate [Å]		30230		10950
Dry volume calculated from model [Å]	Both models	28900		14100
fit	Model 1	0.75		1.07
	Model 2	0.93
Molecular-mass determination
Molecular mass from I(0) in P(r) [kDa]		18±2		10.7±3
Calculated monomeric from sequence [kDa]		23.4		10.3
Calculated monomeric from I(0) in Guinier [kDa]		25±3		11.6
Software employed
Primary data reduction		PRIMUS
Data processing		GNOM
Ab initio analysis		DAMMIF
Model comparison		SUPCOMB
Tertiary structure modelling		RFR (this paper)
Computation of model intensities		CRYSOL
Three-dimensional graphics representations		PyMol