Sulfation of Tyr1680 of human blood coagulation factor VIII is essential for the interaction of factor VIII with von Willebrand factor. - Leyte, A; Van Schijndel, HB; Niehrs, C; Huttner, WB; Verbeet, MP; Mertens, K; van Mourik, JA (J Biol Chem, 1991)