Increased in vitro phosphorylation of rat liver nucleolar proteins following triiodothyronine administration

Summary It has been shown that triiodothyronine (T₃) administration to thyroidectomized rats induces an increase in the in vitro net³²P uptake into liver nucleolar proteins. Such an increase depends on a stimulation of the nucleolusassociated protein kinase activity and not on a lower dephosphorylation rate.We wish to thank MissAdriana Voci for excellent technical assistance. This study was partly supported by a grant from Consiglio Nazionale delle Ricerche (CNR), Italy.