GAP1, the general amino acid permease gene of Saccharomyces cerevisiae

Abstract

In Saccharomyces cerevisiae, mutations at the GAP1 locus selectively abolish the activity of the general amino acid transport system. This permease catalyses active transport of apparently all biological amino acids across the plasma membrane. We have determined the nucleotide sequence of the GAP1 gene. The sequence contains an open reading frame of 601 codons corresponding to a polypeptide of Mr 65578. This polypeptide is strongly hydrophobic; it exhibits three potential glycosylation sites. Hydropathy analysis suggests 12 membrane‐spanning regions. The N‐terminal domain is charged, it does not resemble hydrophobic signal sequences found in secreted proteins. Hence the GAP1 gene encodes a protein with characteristics typical of integral membrane proteins translocating ligants across cellular membranes. The deduced amino acid sequence of GAP1 protein presents strong similarities to those of the yeast arginine, histidine and proline permeases, suggesting a common evolutionary origin for these amino acid permeases. Nitrogen‐source regulation of the GAP1 permease is believed to occur at two distinct levels, i.e. permease synthesis and permease activity [Grenson (1983) Eur. J. Biochem. 133, 135–139]. Northern analysis of GAP1‐specific transcripts in wild‐type and in mutant strains is in agreement with these views and indicates that nitrogen catabolite repression of GAP1 synthesis occurs at the RNA level.

Effect of 21 Different Nitrogen Sources on Global Gene Expression in the YeastSaccharomyces cerevisiae

“…3A) and for which NCR is the main (if not the sole) known transcriptional regulation. This category includes GAP1, which codes for the general amino acid permease (67) and has been the focus of many studies aimed at deciphering the molecular mechanisms of NCR (26,85). It also includes three of the four genes (GAT1/NIL1, DAL80/UGA43, GZF3/DEH1/NIL2) coding for the GATA transcription factors involved in the transcriptional control of NCR target genes (26,85), shown in previous studies to be under NCR control and interlinked in a network of trans-and auto-regulation systems (12,23,109,119).…”

Permease Recycling and Ubiquitination Status Reveal a Particular Role for Bro1 in the Multivesicular Body Pathway

“…Upon addition of a preferential nitrogen source like ammonium (NH 4 ϩ ), the GAP1 gene is repressed, and the permease present at the cell surface is rapidly poly-ubiquitinated on two lysine residues in the N-terminal tail (Lys-9 and Lys-16). This ubiquitination triggers Gap1 endocytosis followed by sorting to the vacuole/lysosome lumen for degradation (17)(18)(19)(20)(21)(22). Ubiquitination of Gap1 at the cell surface is dependent on the ubiquitin ligase Rsp5/Npi1, the Bul proteins, and the Doa4/Npi2 ubiquitin hydrolase, the latter being required to maintain a normal level of free ubiquitin (19,20,22,23).…”

Amino acids regulate the intracellular trafficking of the general amino acid permease of Saccharomyces cerevisiae

“…Gap1p is a high-capacity permease that can transport all naturally occurring amino acids (5,6). GAP1 transcription is positively regulated by the GATA-type transcription factors Gln3p and Gat1p͞Nil1p and negatively regulated by the cytoplasmic factor Ure2p, so that GAP1 is expressed on nonpreferred nitrogen sources but repressed on preferred nitrogen sources (1).…”