P. Lucero et R. Lagunas, CATABOLITE INACTIVATION OF THE YEAST MALTOSE TRANSPORTER REQUIRES UBIQUITIN-LIGASE NPI1 RSP5 AND UBIQUITIN-HYDROLASE NPI2/DOA4/, FEMS microbiology letters, 147(2), 1997, pp. 273-277
The maltose transporter in Saccharomyces cerevisiae is degraded in the
vacuole after internalization by endocytosis when protein synthesis i
s impaired and a fermentable substrate is present. The possible implic
ation of the ubiquitin pathway in this inactivation, known as cataboli
te inactivation, has been investigated. Using mutants deficient in npi
1/rsp5 ubiquitin-protein ligase and npi2/doa4 ubiquitin-protein hydrol
ase, we have shown that these two enzymes are required for normal endo
cytosis and degradation of the transporter. These facts indicate that
the ubiquitin pathway is involved in catabolite inactivation of the ma
ltose transporter. The results also revealed that both enzymes act in
the internalization step of endocytosis.