Molecular cloning of the NA+/K+-ATPase and its implication for bilaterian phylogeny

• Applicant: Professorin Dr. Kristina Kusche-Vihrog
• Subject Area: Evolution, Anthropology
• Term: from 2004 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5446141

The phylogenetic relationship of protostomians has been in controversial discussion for many years. There are two hypotheses of evolution: the classical model, uniting arthropods and annelids in a common clade named Articulata and the molecular based model, which divided the Protostomia into two new clades: Ecdysozoa and Lophotrochozoa. It was shown that proteins central physiological roles are powerful tools for phylogenetic analyses. Sinnce the NA+/K+-ATPase has a highly conserved structure, it is an exellent marker for studies on phylogenetic relationships. In this project we will clone Na+/K+-ATPases from different species and use the amino acid sequences for phylogenetic and functional analyses. The NA+/K+-ATPase is a member of the p-type family of cation-transporting proteins, located in the basolateral membrane of almost all eucaryotic cells, and it is reponsible for the regulation of cell volume and homeostasis. It maintains gradient of Na+ and K+ across the membrane ot cells, and these electrochemical potentials are required for secondoary active transport of other solutes e.g. the transcullulare transport processes in intestine, glads and kidney. First we will concentrate on the molecular cloning and phylogenetic analysis of the Na+/K+-ATPases from molluscs, arthropods, onychophorans and tunicates. For the investigation and comparison of the functional and electrophysiological poperties of NA+/K+-ATPases from different species we will express specific RNA in oocytes from Xenopus laevis.

• DFG Programme: Research Grants