Ca2+ signals:
Molecular Mechanisms and Integrative Functions Collaborative Research Center 894

Project A11 - Dieter Bruns

Complexin and Synaptotagmin in exocytosis

Complexin II (CpxII) and synaptotagmin I (SytI) are key regulators of the SNARE protein-mediated exocytosis. However, their mode of actions and their possible interplay are still largely unknown. In the current funding period we provided first evidence for the synergistic action of different CpxII domains in synchronous transmitter release. In addition, we could demonstrate a functional antagonism of CpxII and SytI at the moment of fusion pore opening.

Based on these results, we intend to delineate the precise mechanisms of CpxII action and how it is influenced by SytI in the context of a detailed structure-function analysis. This goal will be achieved, starting from the corresponding null mutants (single and double null mutants), by a combination of electrophys-iological, biochemical and high-resolution fluorescence microscopic techniques.