[1] Gladstone Inst Cardiovasc Dis, San Francisco, CA 94158 USA
[2] Univ Calif San Francisco, Dept Biochem & Biophys, San Francisco, CA 94158 USA
[3] Univ Calif San Francisco, Dept Med, San Francisco, CA 94158 USA
[4] Max Planck Inst Biochem, D-82152 Martinsried, Germany