Isoprenaline-induced transcription of 4 beta-galactosyltransferase is inhibited by both cycloheximide and actinomycin D in rat parotid acinar cells.

A cDNA clone for the Golgi enzyme 4 beta-galactosyltransferase (EC 2.4.1.38) was used to determine the steady-state mRNA content in cultured rat parotid acinar cells. Isoprenaline, a beta-adrenergic-receptor agonist, caused an increase in steady-state amounts of mRNA for 4 beta-galactosyltransferase in cultured acinar cells as well as in specific activity of the enzyme. The amount of 4 beta-galactosyltransferase-specific mRNA was dependent on transcription of the gene, as determined by incubation of cells with the RNA polymerase inhibitor actinomycin D, concomitant with the time of isoprenaline treatment. Transcription of the 4 beta-galactosyltransferase gene also required the active biosynthesis of additional cellular factors, since isoprenaline-induced increases in mRNA amounts were not observed on co-incubation with the protein-synthesis inhibitor cycloheximide.