Biphasic increase in the in vivo phosphorylation of nuclear 110-kDa protein during early lymphocyte transformation

Abstract
A major 110-kDa [kilodalton] phosphoprotein (P 110) in rat liver and hepatoma was identified in nuclear 0.2 M HCl extracts from rat lymph node cells. Stimulation with concanavalin A altered both the amount of P110 and its in vivo phosphorylation in a typical biphasic manner with an initial maximum after 10-14 h. RNA synthesis showed a similar biphasic increase. Inhibition of hn[heterogeneous nuclear]RNA synthesis (5,6-dichlorobenzimidazoleriboside), but not of DNA synthesis (hydroxyurea), markedly depressed both the amount of P110 and its phosphorylation.