J. Biol. Chem., Vol. 284, Issue 28, 18715-18725, July 10, 2009
The C Terminus of Na+,K+-ATPase Controls Na+ Affinity on Both Sides of the Membrane through Arg935
J. Biol. Chem. Toustrup-Jensen et al. 284: 18715
Mads S. Toustrup-Jensen
Current Position: Associate Professor in the Department of Physiology and Biophysics, Faculty of Health Sciences at Aarhus University in Denmark
Education: Ph.D. in Medicine (2003) from Aarhus University in Denmark (Department of Physiology and Biophysics, Faculty of Health Sciences); M.Sc. in Molecular and Cellular Biology (1997) from University of Southern Denmark
Non-scientific Interests: Diving, tennis, hiking, and nature
I have always been fascinated by the wonders of nature, and became very interested in biochemistry and molecular biology during my high school years. I started my scientific career by mapping the mating type locus in barley powdery mildew fungus. My interest in membrane transport, and in particular P-type ATPases, started in 1997 when I met professors Bente Vilsen and Jens Peter Andersen in the Department of Physiology and Biophysics at Aarhus University. They became my supervisors and collaborators. In 2003, I defended my Ph.D. thesis, "Structure-function relationship of the A-M3 sector of Na+,K+-ATPase studied by site directed mutagenesis," which was selected as the best Ph.D. thesis of the year from the Faculty of Health Sciences at Aarhus University.
My work focuses on structure-function relationships of the Na+,K+-ATPase studied by site-directed mutagenesis. In our lab, we spent many years developing a variety of assays (including fast kinetic measurements at a millisecond time scale) for measuring the individual partial reaction steps in the Na+,K+-ATPase pump cycle of mutants expressed in cell culture. This allows us to detect specific functional effects of amino acid substitutions, and we have become able to distinguish direct effects of mutations on cation binding from indirect effects due to changes in conformational equilibria. Recently (Nature 450:1043-1049, 2007), we found that the C terminus of the Na+,K+-ATPase occupies a unique position in the protein, and I showed that truncation of the C terminus interferes with Na+ binding. In the present work, we reveal details of the interactions of the C terminus and demonstrate that it controls the Na+ affinity on both sides of the membrane. We speculate that the C terminus may constitute a central element of the mechanism that reorients one of the three Na+ sites during ion pumping.
Read Dr. Toustrup-Jensen's article on page 18715.
Files in this Data Supplement:
- Mads Toustrup-Jensen profile - this page as PDF