Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de|Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de|Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de|Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de|Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de|Department of Membrane Biochemistry, Max-Planck Institute for Biochemistry, Martinsried, Germany. gonzalez@biochem.mpg.de