Synchrotron SAXS data from solutions of MLL1-WDR5-ASH2L-RBBP5(2-538) in 300 mM NaCl, 25mM Tris-HCl, 4% glycerol, 1 mM TCEP, pH 8 were collected on the BL19U2 beam line at the Shanghai Synchrotron Radiation Facility (SSRF; Shanghai, China) using a Pilatus 1M detector at a sample-detector distance of 2.4 m and at a wavelength of λ = 0.0918 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 2.00 mg/ml was measured at 9.9°C. 20 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.