Toward a minimal allosterically regulated ADAMTS13. (A) Scattering profiles (black) and P(r) plots (inset) for pADAMTS13, delT3-6, and human ADAMTS13. P(r) plots for MDTCSq (red) and ADAMTS13 (FLq: blue) are included for comparison with those for other constructs (green). (B) Ab initio models (gray surface) calculated from scattering profiles for pADAMTS13, human delT3-6, and human ADAMTS13 superimposed on atomic models of MDTCS (orange = M domain; yellow = D domain; green = T1 domain; sky blue = C domain; lavender = S domain), Ts (surface), and CUBs. T2, green; T3, yellow; T4, green; T5, green; T6, yellow; T7, dark green; T8, green; linker between T8 and CUBs, gray; CUB domains, red and brick red.