A cDNA encoding the 60 kDa subunit of mammalian splicing factor SF3a has been isolated. The deduced protein sequence reveals a 30% identity to the PRP9 splicing protein of the yeast S.cerevisiae. The highest homology is present in a zinc finger-like region in the C-terminal domain of both proteins. The PRP9 zinc finger-like motif has been replaced by the equivalent region of mammalian SF3a60. The chimeric protein rescues the temperature-sensitive phenotype of the prp9-1 mutant strain demonstrating that not only the structure but also the function of this domain has been conserved during evolution.