[1] Washington Univ, Sch Med, Dept Biochem & Mol Biophys, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, Dept Internal Med, St Louis, MO 63110 USA
[3] Washington Univ, Sch Med, Dept Cell Biol & Physiol, St Louis, MO 63110 USA
[4] Washington Univ, Sch Med, Dept Chem, St Louis, MO 63110 USA