Yeast rgs1 cells accumulate secretory vesicles in the cytoplasm and stop the secretion of proteins at the restrictive temperature. The ts mutation rgs1 may be suppressed by several different genes; the S. cerevisiae SEC4 gene, encoding the small G-protein involved in the late secretory stage, is one of them. Synthetic lethality of the double rgs1 sec4 mutant is demonstrated.