Identification of ubiquitin in seminal plasma from Tilapia, Oreochromis niloticus

The polypeptide ubiquitin, up to now almost exclusively discovered in intra cellular spaces, was immunologically detected in Tilapia seminal plasma. Ub iquitin was purified from seminal plasma by column chromatography. N-termin al amino acid sequence analysis revealed 31 N-terminal amino acids to be id entical between this ubiquitin and those of several species. Thus, we concl uded that the protein detected in seminal plasma is a ubiquitin.