FIG. 3.

Gentamicin sensitivities of yeast Arf GAP mutants. AGE1, AGE2, GLO3, and GCS1 encode the four GTPase-activating proteins (GAPs) associated with Arf function. None of these genes is essential, but the Age2/Gcs1 pair and the Glo3/Gcs1 pair are essential. Spot dilution assays were performed with the indicated numbers of cells, which were grown for 3 days on solid YPD medium. All strains contain a temperature-sensitive allele of GCS1, but only strains with defective GAP pairs are sensitive to gentamicin at the permissive temperature of 25°C.