Fig. 1. Protein translocation into the ER of the Antarctic yeast C. adeliensis and the mesophilic yeast S. cerevisiae. Upper: limiting amounts of microsomal protein were incubated with excess radiolabelled secretory precursor (pgpf) for 0 (lanes 1, 5) or 15 minutes (all other lanes) at the indicated temperatures and samples analyzed by SDS-PAGE. Signal-cleavage (gpf) was used as a measure of translocation and was quantified using a phosphorimager. Signal-cleaved gpf was >90% protease protected. Samples were taken in duplicate, and the experiment repeated twice. The difference between translocation at different temperatures is indicated (x). Lower: translocation at 20°C for each species was set to 100% to illustrate the relative decrease in translocation efficiency with decreasing temperature.

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