Rates of turnover of deoxythymidine kinase and of its template RNA in regenerating and control liver.

Deoxythymidine kinase levels in liver were maximally en hanced by 12-fold at 24 hr after partial hepatectomy while aspartate transcarbamylase reached maximum activity by 48 hr. The rates of turnover of deoxythymidine kinase and of its tem plate RNA were studied with the use of cycloheximide and actinomycin D, respectively. The half-life (tj) of the template RXA for deoxythymidine kinase in 24-hour regenerating and control adult liver was 7.5 and 3.0 hours, respectively. The tj for aspartate transcarbamylase template RNA was >24 hours in both regenerating and control adult liver. The rates of turnover of deoxythymidine kinase in regenerating and control livers were determined; the tj was 3.7 and 2 6 hr, respectively. It is concluded that immediately following partial hepatec tomy, a substance is elaborated which may prolong the life of the deoxythymidine kinase messenger RNA by inactivating a catabolic mechanism and in this manner may ultimately lead to a greater intracellular concentration of enzyme.