The role of BARS/CtBP3, a protein involved in Golgi membrane fission, in intracellular membrane transport in vivo

Bonazzi, Matteo (2005). The role of BARS/CtBP3, a protein involved in Golgi membrane fission, in intracellular membrane transport in vivo. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f627

Abstract

In the context of intracellular membrane transport the main focus of interest has been concentrated on the processes regulating fission and fusion of membranous transport carriers. If on one hand there seems to be a unique, conserved machinery regulating fusion of all transport intermediates with their respective acceptor compartments, at the level of membrane fission there still remains much uncertainty. At least the Dynamin family of proteins has been identified as a regulatory component for a number of fission events but this is certainly not universal. There are a number of fission steps in the transport pathway that are clearly independent of dynamin and this raises the possibility that there are multiple machineries regulating membrane fission in different transport pathways. Based on the observation that the protein QBP3/BARS (BARS) is able to induce fission, in vitro, of Golgi-derived membranous tubules, the present study aims to characterise the relevance of this effect on multiple intracellular transport steps in the intracellular environment. BARS is found to be involved in post-Golgi protein transport to the basolateral plasma membrane and also in fluid phase endocytosis and this confirms the existence of a novel fission-inducing machinery. In addition, since the selective inhibition of either one of these two pathways (i.e. those regulated by dynamin or BARS) has no effect on the operation of the other, it is concluded that they operate independently.