Reduced Temperature Can Block Different Glycoproteins at Different Steps during Transport to the Plasma Membrane

Reduced temperature has been shown to block the cell surface expression of Sendai virus haemagglutinin-neuraminidase (HN) and fusion (F₀) glycoproteins at different steps of their intracellular transport. At 20 °C, HN was confined to the rough endoplasmic reticulum or cis Golgi compartment, while F₀ acquired complete resistance to digestion by endo--N-acetylglucosaminidase-H and therefore was blocked at a more distal location in the pathway of cell surface expression. The significance of these results for different pathways of transport to the cell surface is discussed.