Small G proteins and the organisation of the Golgi apparatus
The compartments of the secretory and endocytic pathways are connected by membrane-bound carriers that bud from, and then fuse with, specific organelles. The accuracy of this traffic depends on the organelles having an 'identity' by which the trafficking machinery can recognise them. This identity is defined by organelle-specific G proteins of the Arf and Rab families and by phosphoinositide lipids.
We are interested in how active G proteins are generated in a spatially restricted manner, and what cytosolic proteins or 'effectors' then recognise them.
Our work is focussed on the Golgi apparatus, an organelle that plays a central role in the sorting and modification of proteins in the secretory pathway. The Golgi contains a number of Arf and Rab proteins, and we apply biochemical and genetic methods to identify their interacting partners in both cultured cells and yeast.
One major class of effector that we are investigating are the long coiled-coil proteins that are believed to act in the tethering of carriers prior to fusion.
An understanding of how organelle identity is established and recognised is only starting to emerge but promises to reveal much about the underlying logic of the organisation of eukaryotic cells.