Professor Ago Rinken, University of Tartu
Professor Tatsuya Haga, University of Tokyo, Japan
The aim of this thesis was to investigate signal transduction mechanisms that are mediated by G-protein coupled receptors. These receptors are located in the cell membrane, where they receive extracellular signals and relay them to intracellular guanine nucleotide binding proteins (G-proteins). G-protein coupled receptors play a major role in regulating numerous physiological processes - from embryonal cell differentation to fine-tuning the activity of the central nervous system - and are therefore important drug targets.
G-proteins are responsible for relaying the signals that receptors detect to various intracellular effector systems. Our objective was to compare how various G-protein subtypes differ in their properties, especially in their ability to bind nucleotides and also how their activity is modulated by receptors (like the serotonin 1A receptor) and manganese ions. In order to meet these objectives, several novel methods were developed for both purifying G-proteins and for determining their activity in either their purified form or in complex with receptors in baculovirus particles.