The rat Prm3 gene is an intronless member of the protamine gene cluster and is expressed in haploid male germ cells.

We have cloned and sequenced the cDNA of a novel gene from the rat protamine gene cluster. This gene, preliminarily referred to as Prm3, is intronless and resides between the genes for protamine 2 and transition protein 2. Prm3 is transcribed from the same strand as these genes and is expressed in haploid stages of spermatogenesis. The 410-bp-long cDNA possesses an ORF, coding for a putative 104-amino acid polypeptide with a high content of glutamic acid.