Pisum sativump16 is a protein present in the chromatin of ungerminated embryonic axes. The purification of p16 and the isolationof a cDNAclone ofpsp54, the gene encoding its precursor have been recently reported [Castillo, J., Rodrigo, M. I.,Ma´rquez, J. A., Zu´n˜iga, AandFranco, L. (2000)Eur. , 2156–2165]. In thepresentpaper,wepresent data showing that p16 is a nuclear protein.