PAS genes are required for peroxisome biogenesis in the yeast S. cerevisiae. Here we describe the cloning, sequencing, and characterization of the PAS1 gene. Its gene product, Pas1p, has been identified as a rather hydrophilic 117 kd polypeptide. The predicted Pas1p sequence contains two putative ATP-binding sites and reveals a structural relationship to three other groups of proteins associated with different biological processes such as vesicle-mediated protein transport (NSF and Sec18p), control of cell cycle (Cdc48p, VCP, and p97-ATPase), and modulation of gene expression of the human immunodeficiency virus (TBP-1). The proteins share a highly conserved domain of about 185 amino acids including a consensus sequence for ATP binding. We suggest that these proteins are members of a novel family of putative ATPases and may be descendants of one common ancestor.