Structure of thrombospondin. The fragments are arranged about the main cleavage points at T²³⁸ and G⁹⁵¹ and the additional cleavage site approximately 60 residues (6 kD) from the C-terminus. The multiple cysteines (Cys) with potential thiols are within the calcium binding region (type 3 repeats) of thrombospondin.10