A gene encoding a homologue of the ADP-ribosylation factor (ARF) family of small GTP binding proteins was cloned from a Schizosaccharomyces pombe cDNA library by a functional screen of suppressors of sensitivity to 3-aminotriazole in a gcn3 null strain of Saccharomyces cerevisiae. Two independent isolates each contained the full coding region of the ARF1 gene. The encoded SpARF1 protein has a predicted molecular weight of 20,618 and is 88% and 79% identical to human and S. cerevisiae ARF1 proteins, respectively. As independent isolates were obtained, this effect of the SpARF1 appears to be a real phenomenon, but cannot currently be easily understood within the context of the evidence for a role(s) for ARF proteins in the protein secretory pathway.