REGULATION OF THE TRANSLATION AND PROCESSING OF RAT DOPAMINE-BETA-HYDROXYLASE BY METAL-IONS IN A CELL-FREE SYSTEM

Metal ions play an important role in the metabolism of prokaryotic and eukaryotic cells. In this study we examine the effect of various meta l ions on the translation, glycosylation and co-translational processi ng of dopamine beta-hydroxylase (DBH) in vitro. The translation of wil d type DBH mRNA and constructs with site directed mutations near the p utative signal cleavage site was carried out with the addition of diff erent ions (Mg2+, Cu2+, Mn2+, Ni2+, Co2+, Zn2+, Pb2+, Fe2+, Fe3+, Ca2) in a cell-free system in the present of microsomal membranes. Most o f the metal ions inhibited translation at concentrations above 1.5 mM. The translation was more sensitive to Fe2+ than Fe3+. Ni2+ and Cu2+ p referentially inhibited formation of the glycosylated products. Only m agnesium affected the ratio of the two different processed forms in a concentration dependent manner.