Structural basis for the inactivity of human blood group o2 glycosyltransferase Lee, H.J. , Barry, C.H. , Borisova, S.N. , Seto, N.O.L. , Zheng, R.B. , Blancher, A. , Evans, S.V. , Palcic, M.M. J.Biol.Chem. 280 pp. 525 (2005)