Functional studies of sodium pump isoforms

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

The Na+,K+-ATPase is an essential ion pump found in all animal cells. It uses the energy from ATP hydrolysis to export three Na+ and import two K+, both against their chemical gradients and for Na+ also against the electrical potential. Mammals require four Na+,K+-ATPase isoforms that each have unique expression profiles and specialized functional features. We use a Two Electrode Voltage Clamp setup to determine pre-steady-state and steady-state characteristics of each isoform and design chimeras to pin-point the structural elements responsible for observed differences. With this strategy we have found that a sperm specific Na+,K+-ATPase isoform is adapted to withstand fluctuations in the extracellular solution, which is in accordance with the physiological role of the sperm cell. We have used a chimeric Na+,K+-ATPase to determine that part of this specialization comes from having a hydrophobic external ion entrance/exit vestibule instead of a negatively charged which is characteristic for the other isoforms. We hope that this approach can help us answer the long asked question of whether the three Na+ leaves through a common exit pathway, or if one use an exclusive channel.
Neurons and glial cells express multiple isoforms of the Na+,K+-ATPase that are sorted to different specialized subcellular compartments. We are setting up a novel assay to study the details of Na+,K+-ATPase trafficking in polarized cells. With SNAP and CLIP tagged Na+,K+-ATPase isoforms we can track newly synthesized cohorts of pumps from the Golgi apparatus to the plasma membrane.
ForlagAarhus University, Faculty of Science and Technology
Antal sider150
StatusUdgivet - 2012

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