The establishment and maintenance of ion gradients across the plasma membrane, which separates a cell from its environment, and across the membranes enclosing subcellular compartments is of pivotal importance for innumerable physiological functions of the cell and its organelles. For example, the acidification of endosomes and lysosomes is required for enzyme activity and for membrane traffic in this subcellular pathway. Ion transport processes underlie the excitability of cells and are crucial for cell volume regulation, cell migration and transport of other substances. The homeostasis of specific ion concentrations, osmolarity and volume of the various compartments is accomplished by a plethora of ion-transporting proteins whose activities have to be tightly regulated.
The main interest of our group is to quantitatively understand this complex system of cellular and subcellular ion homeostasis and its connection to cell physiological functions. We aim at identifying unknown ion transporters or channels and their regulators; we characterize ion transporters on a biochemical, biophysical and cell biological level; we investigate how ion transporters determine cellular and vesicular ion homeostasis; and finally we examine the effect on cellular and even organismal physiology. To this end we use an interdisciplinary systems biology approach with a broad range of methodologies including siRNA screening, molecular biology, protein biochemistry, cell culture and microscopy, biophysical approaches like ion imaging, histology of animal models, and mathematical modelling.