Assembly of mitochondrial F1-ATPase in Saccharomyces cerevisiae requires the molecular chaperone, Atp11p. Database searches have identified protein sequences from Schizosaccharomyces pombe and two species of Drosophila that are homologous to S. cerevisiae Atp11p. A cDNA encoding the putative Atp11p from Drosophila yakuba was shown to complement the respiratory deficient phenotype of yeast harboring an atp11::HIS3 disruption allele. Furthermore, the product of this Drosophila gene was shown to interact with the S. cerevisiae F1 beta subunit in the yeast two-hybrid assay. These results indicate that Atp11p function is conserved in higher eukaryotes.