Synchrotron SAXS data from solutions of the tandem WW domains of PRPF40A in complex with SF1 in 20 mM sodium phosphate, 100 mM NaCl, 0.5 mM DTT, pH 6.5 were collected on the BM29 beam line at the ESRF (Grenoble, France) using a Pilatus3 2M detector at a sample-detector distance of 2.8 m and at a wavelength of λ = 0.099186 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). In-line size-exclusion chromatography (SEC) SAS was employed. The SEC parameters were as follows: A 50.00 μl sample at 10.5 mg/ml was injected at a 0.16 ml/min flow rate onto a Agilent Bio SEC-3, 300 Å column at 25°C. 44 successive 1 second frames were collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.