An endosomal βCOP is involved in the pH-dependent formation of transport vesicles destined for late endosomes

Abstract

In this paper, we show that βCOP is present on endosomes and is required for the formation of vesicles which mediate transport from early to late endosomes. Both the association of βCOP to endosomal membranes as well as transport vesicle formation depend on the lumenal pH. We find that εCOP, but not γCOP, is also associated to endosomes, and that this association is also lumenal pH dependent. Our data, thus, indicate that a subset of COPs is part of the mechanism regulating endosomal membrane transport, and that membrane association of these COPs is controlled by the acidic properties of early endosomes, presumably via a trans-membrane pH sensor.