We have isolated both cDNA and genomic clones for the 73 kDa subunit of the DNA polymerase alpha primase of Drosophila melanogaster. Analysis of these clones has identified an open reading frame of 1959 bases coding for a protein of 72.5 kDa. Northern analysis has shown the mRNA for the gene to be approximately 2.5 kb, and comparison of the cDNA and the genomic clones shows that the coding region of the gene lacks introns. The 5' end of the transcript has been mapped by primer extension, and the position of the gene in the genome mapped using in situ analysis. Computer analysis has been carried out on both coding and non coding regions of the gene. The protein sequence shows some homology to the analogous subunit in the S. cerevisiae DNA polymerase alpha, however a search of the data banks failed to reveal other homologies, or provide any clues as to the function of the protein. Analysis of the non-coding regions indicates some potential control regions for the gene. The 73 kDa protein has been overproduced, but a preliminary analysis failed to reveal any enzymatic activities.