LTBP-1ΔC specifically co-aggregates with mutant Notch3. a Notch3-ECD multimer formation is monitored by SIFT and data illustrated in a 2D histogram: axes represent the intensity of photons per bin in the detector channel (green channel along the x-axis, red channel along the y-axis). While monomers and homomeric multimers result in data points in the lower left histogram area and along the axes respectively, heteromeric multimers are represented as high-intensity, dual-color signals in the white sector. b Purity of proteins used in the aggregation assay. Shown are silver-stained gels containing the elution fractions after metal-ion matrix (LTBP-1ΔC or LTBP-1ΔN) or Halo-tag-mediated purification (N3EGF1-5 R183C). c SIFT data from different protein combinations: while no high-molecular-weight particles are detected with N3EGF1-5 WT, typical aggregates are formed by N3EGF1-5 R183C and when combined with LTBP-1ΔC. In all other combinations homomeric multimers are detected indicating self-aggregation. Shown are representative images of 2–5 experiments. WT: wild-type.