Species- and Tissue-specific Patterns of Phosphorylation of Very Lysine-rich Histones

Purified very lysine-rich histones (histone I) from trout testis, liver, and erythrocytes, frog liver and erythrocytes, chicken liver and erythrocytes, rabbit liver, and calf thymus were phosphorylated by trout testis protamine kinase and γ-32P-ATP. The extent of phosphorylation obtained varied widely for the different histones I. Autoradiography after tryptic digestion and paper electrophoresis of the phosphorylated histones revealed several different major phosphopeptides from the nine tissues examined. Differences were found both in the phosphopeptide pattern of histone I from different organs in the same species and from the same organ in different species. Rat liver histone kinase phosphorylated the same major site in trout testis histone I as did protamine kinase.