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Addition of ammonium ions to yeast cells growing on proline as the sole nitrogen source induces rapid inactivation and degradation of the general amino acid permease Gap1 through a process requiring the Npi1/Rsp5 ubiquitin (Ub) ligase. In this study, we show that NH4+ induces endocytosis of Gap1, which is then delivered into the vacuole where it is(More)
The yeast ubiquitin ligase Npi1/Rsp5 and its mammalian homologue Nedd4 are involved in ubiquitination of various cell surface proteins, these being subsequently internalized by endocytosis and degraded in the vacuole/lysosome. Both enzymes consist of an N-terminal C2 domain, three to four successive WW(P) domains, and a C-terminal catalytic domain (HECT)(More)
When yeast cells growing on a poor nitrogen source are supplied with NH4+ ions, several nitrogen permeases including the general amino acid permease (Gap1p) are rapidly and completely inactivated. This report shows that inactivation by NH4+ of the Gap1 permease is accompanied by its degradation. A functional NPl1 gene product is required for both(More)
Addition of ammonium ions to yeast cells growing on proline as the sole nitrogen source induces internalization of the general amino acid permease Gap1p and its subsequent degradation in the vacuole. An essential step in this down-regulation is Gap1p ubiquitination through a process requiring the Npi1p/Rsp5p ubiquitin ligase. We show in this report that(More)
Ammonium uptake in the yeast Saccharomyces cerevisiae involves three membrane transporters (Mep1, -2 and -3) belonging to an evolutionarily conserved protein family that also includes the rhesus (Rh) blood group polypeptides of erythrocytes. We show here that, in the 26972c mutant defective in NH4+ transport, the Mep1 protein carrying an amino acid(More)
A new repeating amino acid motif, which we called WWP, was found in several proteins of yeast, nematod or vertebrate origin. Among these are dystrophin, the product of the Duchenne muscular dystrophy locus, a protein (YAP65) which associates in vitro with the Src homology domain 3 (SH3) of the Yes proto-oncogene product, and a human putative(More)
The membrane traffic and stability of the general amino acid permease Gap1 of Saccharomyces cerevisiae are under nitrogen control. Addition of a preferential nitrogen source such as ammonium to cells growing on a poor nitrogen source induces internalization of the permease and its subsequent degradation in the vacuole. This down-regulation requires(More)
Methionine increased the intracellular glutathione (reduced) (GSH) pool and the specificγ-glutamyltransferase (γ-GT) activity in the cephalosporin C (CPC) producerAcremonium chrysogenum. The accelerated turnover of GSH might be indicative of the existence of a functioningγ-glutamate cycle, and might supply the CPC biosynthetic machinery withl-cysteine.(More)
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