Extraordinarily high density of unrelated genes showing overlapping and intraintronic transcription units

Abstract

The cloning of pyrroline 5-carboxylate reductase from Drosophila melanogaster was accomplished by cDNA complementation of an Escherichia coli proline auxotroph. The corresponding P5cr gene is tightly clustered with three other expressed coding regions. A bidirectional promoter, an overlapping 3′UTR and an intraintronic sequence may all be found in only 4.3 kb, making this the most densely clustered region of unrelated genes in any eukaryote.