SS33410, an Inhibitor of V-ATPase, Blocks Intracellular Protein Transport of the VSV-G Protein in the Golgi Compartment

Abstract

An earlier report suggested that SS33410, structurally related to folimycin and bafilomycin A₁, blocked secretion of the glycoprotein (G protein) of vesicular stomatitis virus (VSV) into the medium and, instead, G protein was accumulated intracellulary. To identify the inhibition site of SS33410 in intracellular protein transport, I have analyzed the oligosaccharide chain structure of the intracellularly accumulated G protein. In SS33410-treated VSV-infected cells, G protein oligosaccharide was suggested to have a composition of GlcNAc-Man₅-GlcNAc₂ as analyzed by Bio-Gel P-4 column chromatography following digestion with α-mannosidase, β-N-acetylhexosaminidase, and then with α-mannosidase. SS33410 specifically inhibited vacuolar-type ATPase (V-ATPase). These studies thus suggest that SS33410 blocks the intracellular protein transport before the step of trimming by mannosidase II, which is confined to the medial Golgi compartment.

• protein transport
• VSV-G protein
• vacuolar type ATPase
• Golgi apparatus
• glycoprotein