THE EFFECT OF PROTEIN-SYNTHESIS INHIBITORS ON THE GLYCOSYLATION SITE OCCUPANCY OF RECOMBINANT HUMAN PROLACTIN

The relationship between synthesis and N-linked glycosylation site occ upancy of recombinant human prolactin produced from C127 cells was stu died with the aid of a battery of protein synthesis inhibitors. Non-le thal concentrations of sodium fluoride, gougerotin, puromycin, anisomy cin, and emetine did not alter site occupancy, but low concentrations (<10 mu g ml(-1)) of cycloheximide increased the fraction of secreted prolactin bearing oligosaccharide from 20% to 80% of the total. Cycloh eximide is an inhibitor of the elongation step of protein synthesis. T he observed increase in glycosylation site occupancy upon addition of cycloheximide is consistent with the current opinion that the initial glycosylation event occurs cotranslationally during a limited time per iod. Cycloheximide may extend this time period by reducing elongation rate. However, the absence of any effect from treatment with other inh ibitors of elongation suggests that cycloheximide is unique in its beh avior on this system.