Apparent inhibition of glycoprotein synthesis by S.cerevisiae mating pheromones

Abstract
Saccharomyces cerevisiae mating pheromones a and α factor strongly inhibit the incorporation of radio-labelled glucosamine into N-glycosylated proteins of corresponding haploid cells. This observation was erroneously interpreted as an inhibition of glycoprotein synthesis. It has turned out that α factor causes a 4–5-fold dilution of incorporated [14C]glucosamine with non-radioactive endogenous precursor. In the case of the [14C]chitin synthesized, which does not show inhibition by α factor, the lowering of the specific activity of the precursor is exactly compensated for by an increased rate of chitin synthesis caused by α factor.