[Purification and characterization of precursors of mouse protamine mP2]

Mouse protamine 2 (62 residues) is synthesized as a precursor pmP2 (106 residues) which is subsequently processed during the end of spermiogenesis. Three proteins with molecular and electrophoretic properties similar to those of pmP2 were isolated from testis purified nuclei. The comparison of their amino acid composition and of their N-terminal sequence with those of pmP2 shows that the three isolated proteins are products of pmP2 precursor processing. The three intermediate proteins pmP2/5, pmP2/11 and pmP2/20 which contain 102, 96 and 87 residues respectively, are generated from pmP2 precursors after N-terminal excision of 4, 10 and 19 residues, respectively.