Synchrotron SAXS data from solutions of KRAB-associated protein 1 (KAP1); TRIM28, amino acids 23-812 in 20 mM HEPES, 500 mM NaCl, 10 % glycerol, 2 mM TCEP, pH 7.5 were collected using size exclusion chromatography SAXS (SEC-SAXS) on the BM29 beam line at the ESRF (Grenoble, France) using a Pilatus 1M detector at a sample-detector distance of 2.9 m and at a wavelength of λ = 0.099 nm (l(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). SEC-SAXS was performed at 20°C using the following parameters: Column type: GE Healthcare Superose 6 10/300; Flow rate: 0.5 ml/min; Injection volume: 100 µl; Total acquisition time: 60 min (3000 x 1 s frames); Injection concentration: 12 mg/mL. The data obtained through the sample elution peak were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted and the individual subtracted data sets were scaled and averaged to generate the scattering profile displayed in this entry.