Immunocytochemical analysis of the transfer of vesicular stomatitis virus G glycoprotein from the intermediate compartment to the Golgi complex

Abstract

Several independent lines of evidence suggest that the traffic between the ER and the Golgi complex involves other membrane-bound structure that may form distinct compartment(s). These structures have been variously named, but their morphology has yet to be defined, and the mechanism of the transport between the ER and Golgi complex is still largely unknown. To address an aspect of this problem we used G glycoprotein synthesized by the VSV is-045 mutant strain. At the non-permissive temperature (39 °C) G glycoprotein accumulates in the ER as a multimeric aggregate and there is very little export. When the temperature is lowered to 31 °C, the aggregated protein trimerizes, leaves the ER and reachs the Golgi complex; if the temperature is lowered to 15 °C, the protein correctly trimerizes but it is arrested in an intermediate location before reaching the Golgi complex. Here we describe the morphology of this intermediate structure and the transfer of G glycoprotein from this compartment to the Golgi complex.