Isolation and characterization of a cDNA clone encoding testis protamine Z1 from the dog-fish Scylliorhinus caniculus

A clone containing a 445-bp cDNA insert was isolated from a cDNA library synthesized from dog-fish testes mRNA. The nucleotide sequence was determined and corresponded to a 50-amino-acid protein. The known five-amino-acid N-terminal sequence corresponded exactly to our deduced amino acid sequence. After in vitro transcription of this cDNA using SP6 RNA polymerase, the translated polypeptide comigrated with the Z1 scylliorhinine marker. Analysis of the cDNA 3' flanking region of our Scylliorhinus protamine Z1 revealed an inverted repeat sequence, an ACAA motif and a CAGGAAAGA box known as regulatory signals for transcription termination in histone genes. In addition, sequences homologous to the simian virus (SV 40) and polyoma virus core enhancer elements were identified in the 5' and 3' flanking regions.