Figure 1.

Yeast cytosol promotes glycotripeptide export from dog pancreas microsomes. Aliquots (2.5 μl) of dog pancreas microsomes (A₂₈₀ = 30) were incubated with or without ATP and an ATP-regenerating system, and with or without 45 or 200 μg of yeast cytosol derived from RSY255 in 25 μl for the indicated times at 24°C or 32°C. Samples without cytosol contained ATP and the regenerating system, samples without ATP contained 200 μg of yeast cytosol. Membranes were sedimented and glycotripeptide in the supernatant and pellet fractions were quantified by Con A precipitation. All samples were done in duplicate. Glycotripeptide released from the membranes at time zero was subtracted as background from each value. Total glycotripeptide in each sample was ≈100,000 cpm.