Final Activity Report Summary - PAR-1/POLARITY (Combining protein engineering, biochemical and genetic approaches to dissect Par-1 function and regulation in vivo) The establishment and maintenance of cell polarity is a fundamental feature of most eukaryotic cells and is crucial for the generation of cell diversity through asymmetric cell divisions in development and for the proper execution of vectorial cellular functions. Par-1 kinases play instrumental roles in cell polarisation from yeast to humans. Nevertheless, little is known about the molecular mechanisms by which they exert their effects. We used the drosophila oocyte, which was ideally suited for genetic and biochemical manipulation, as a model system to identify Par-1 targets and regulators. In addition we attempted to develop new tools to monitor Par-1 regulation in vivo. We screened for physiological targets of the Par-1 kinase and obtained a list of candidates which was then further narrowed down and characterised. In addition, we created a useful mutant version of the kinase which could be used to detect kinase direct substrates. Given the molecular and functional conservation of Par-1 in eukaryotes, it was likely that interacting partners isolated in drosophila would have similar functions in other organisms, providing insight into the molecular networks through which a fundamental process such as cell polarisation was achieved.
