Molecular cloning of an essential yeast gene encoding a proteasomal subunit

We present the cloning and sequence of a Saccharomyces cerevisiae gene, PUP2, which encodes for a proteasomal subunit. The PUP2 protein is similar to other proteasomal components from yeast, as well as from Drosophila and rat. Although not-properly-folded proteins have been implicated to constitute substrates of proteasomes, we show that the accumulation of such proteins does not induce expression of the PUP2 gene. Finally, gene disruption experiments demonstrate that PUP2 belongs to the class of yeast proteasomal subunits that are essential for cell viability.