Forschungsprofil Prof. Dr. Klaus Fendler

Prof. Dr. Klaus Fendler
  • Dr. rer. nat. (Solid State Physics) University of Konstanz, 1983
  • Habilitation (Biophysical Chemistry) University of Frankfurt, 1995
  • Adjunct Professor, University of Frankfurt, 2003
  • At the Institute since 1983




Transport mechanism of ion translocating membrane proteins

SSM-based Electrophysiology: We are investigating a number of membrane proteins that perform active transport of charged substrates over the cell membrane. For this purpose we analyze the charge translocation by these proteins using solid supported membrane based electrophysiology (SSM-based electrophysiology). These techniques are supplemented by spectroscopic methods and electrophysiological and uptake measurements using Xenopus oocytes. In order to assess the contribution of single amino acid residues to the transport process, functional analysis of mutants of the transport proteins is performed.

The systems currently under investigation are: bacterial sugar transporters (LacY, FucP, XylE, GlcP) and Na+/H+ exchangers (NhaA, NhaP1, hsNHA1,2).
For the investigation of the bacterial transporters we use reconstituted systems (protein reconstituted in liposomes) or membrane fragment preparations. The advantage of a purified preparation is obvious: no interaction with intracellular components or other membrane proteins, a well controlled lipid environment and a well defined aqueous phase. Membrane fragments are more easily prepared and allow the investigation of the transport protein in its natural environment.


SSM cuvette designed for rapid solution exchange.

Rapid solution exchange: Time-resolved information is important for the investigation of the transport mechanism. We have, therefore, developed a rapid solution exchange SSM system which allows solution exchange at the surface of the SSM within 2 ms.

96-well plate for SSM-based electrophysiology

Drug screening. The SSM is a robust platform which allows parallelization and automation of functional transporter testing. It is, therefore, well suited for the screening of pharmacologically interesting compounds.




Selected Publications:

Bazzone A, Barthmes M, Fendler K (2017) Chapter Two - SSM-Based Electrophysiology for Transporter Research. In: Ziegler C (ed) Methods in Enzymology, vol Volume 594. Academic Press, pp 31-83,

Călinescu O, Dwivedi M, Patino-Ruiz M, Padan E, Fendler K (2017) Lysine 300 is essential for stability but not for electrogenic transport of the Escherichia coli NhaA Na+/H+ antiporter. J Biol Chem 292:7932-7941,

Bazzone A, Madej MG, Kaback HR, Fendler K (2016) pH Regulation of Electrogenic Sugar/H+ Symport in MFS Sugar Permeases. PLoS One 11:e0156392,

Călinescu O, Fendler K (2015) A universal mechanism for transport and regulation of CPA sodium proton exchangers. Biological chemistry 396:1091-1096,

Grewer C, Gameiro A, Mager T, Fendler K (2013) Electrophysiological characterization of membrane transport proteins. Annual review of biophysics 42:95-120,

Garcia-Celma JJ, Smirnova IN, Kaback HR, Fendler K (2009) Electrophysiological characterization of LacY. Proc Natl Acad Sci U S A 106:7373-7378,

Krause R, Watzke N, Kelety B, Dorner W, Fendler K (2009) An automatic electrophysiological assay for the neuronal glutamate transporter mEAAC1. J Neurosci Methods 177:131-141,

Ruitenberg M, Kannt A, Bamberg E, Ludwig B, Michel H, Fendler K (2000) Single-electron reduction of the oxidized state is coupled to proton uptake via the K pathway in Paracoccus denitrificans cytochrome c oxidase. Proc Natl Acad Sci USA 97:4632-4636,

Hildebrandt V, Fendler K, Heberle J, Hoffmann A, Bamberg E, Buldt G (1993) Bacteriorhodopsin expressed in Schizosaccharomyces pombe pumps protons through the plasma membrane. Proc Natl Acad Sci U S A 90:3578-3582, 10.1073/pnas.90.8.3578

Butt HJ, Fendler K, Bamberg E, Tittor J, Oesterhelt D (1989) Aspartic acids 96 and 85 play a central role in the function of bacteriorhodopsin as a proton pump. EMBO Journal 8:1657-1663

Fendler K, Grell E, Haubs M, Bamberg E (1985) Pump currents generated by the purified Na+K+-ATPase from kidney on black lipid membranes. EMBO Journal 4:3079-3085



Max-Planck-Institut für Biophysik

Prof. Dr. Klaus Fendler
Abteilung für Biophysikalische Chemie

Tel.: +49 (0) 69 6303-2035
Fax: +49 (0) 69 6303-2002

E-Mail: fendler(at)


Graduate students:

  • Miyer Patiño-Ruiz