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Gene Review

PTR3  -  Ptr3p

Saccharomyces cerevisiae S288c

Synonyms: APF3, Peptide transport protein 3, RAA2, SPS-sensor component PTR3, SSY3, ...
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High impact information on PTR3

  • Upon detection of external amino acids, Ssy1-Ptr3 likely allows-in a manner dependent on SCF(Grr1)-the Ssy5 endoprotease to gain access to and to cleave Stp1, this requiring prior phosphorylation of Stp1 by casein kinase I [1].
  • Mutations in SSY5 manifest phenotypes that are indistinguishable from those resulting from either single ssy1 and ptr3 mutations or ssy5 ssy1 and ssy5 ptr3 double mutations [2].
  • Genetic and biochemical analysis of the yeast plasma membrane Ssy1p-Ptr3p-Ssy5p sensor of extracellular amino acids [2].
  • Mutations in SSY1 and PTR3 were identified in a genetic selection for components required for the proper uptake and compartmentalization of histidine in Saccharomyces cerevisiae [3].
  • Ssy1p requires the endoplasmic reticulum protein Shr3p, the amino acid permease-specific packaging chaperonin, to reach the PM, whereas Ptr3p does not [3].

Biological context of PTR3


Anatomical context of PTR3


Associations of PTR3 with chemical compounds


Regulatory relationships of PTR3

  • PTR3 was required for amino acid-induced expression of PTR2, the gene encoding the dipeptide/tripeptide transport protein, but was not necessary for nitrogen catabolite repression of peptide import or PTR2 expression [4].

Other interactions of PTR3

  • The PTR system consists of three genes, PTR1, PTR2 and PTR3 [8].
  • However, Stp1 processing does not require SCF(Grr1), Ssy1, or Ptr3 when Ssy5 is overproduced [1].
  • Isolation and screening of 31 additional N-methyl-N-nitro-N-Nitrosoguanidine (MNNG)-induced, peptide transport-deficient mutants produced one ptr3 and 30 ptr2 strains: no additional complementation groups were detected [9].
  • Two plasma membrane-associated proteins, Ptr3p and Ssy5p, participate in the sensing, which results in cleavage of the transcription factors Stp1p and Stp2p, removing 10 kDa of the N terminus of each of them [6].


  1. Amino acid signaling in yeast: casein kinase I and the Ssy5 endoprotease are key determinants of endoproteolytic activation of the membrane-bound Stp1 transcription factor. Abdel-Sater, F., El Bakkoury, M., Urrestarazu, A., Vissers, S., André, B. Mol. Cell. Biol. (2004) [Pubmed]
  2. Genetic and biochemical analysis of the yeast plasma membrane Ssy1p-Ptr3p-Ssy5p sensor of extracellular amino acids. Forsberg, H., Ljungdahl, P.O. Mol. Cell. Biol. (2001) [Pubmed]
  3. Ssy1p and Ptr3p are plasma membrane components of a yeast system that senses extracellular amino acids. Klasson, H., Fink, G.R., Ljungdahl, P.O. Mol. Cell. Biol. (1999) [Pubmed]
  4. PTR3, a novel gene mediating amino acid-inducible regulation of peptide transport in Saccharomyces cerevisiae. Barnes, D., Lai, W., Breslav, M., Naider, F., Becker, J.M. Mol. Microbiol. (1998) [Pubmed]
  5. Mutations in five loci affecting GAP1-independent uptake of neutral amino acids in yeast. Jørgensen, M.U., Bruun, M.B., Didion, T., Kielland-Brandt, M.C. Yeast (1998) [Pubmed]
  6. Constitutive signal transduction by mutant Ssy5p and Ptr3p components of the SPS amino acid sensor system in Saccharomyces cerevisiae. Poulsen, P., Wu, B., Gaber, R.F., Kielland-Brandt, M.C. Eukaryotic Cell (2005) [Pubmed]
  7. Characterization of genes that are synthetically lethal with ade3 or leu2 in Saccharomyces cerevisiae. Nigavekar, S.S., Cannon, J.F. Yeast (2002) [Pubmed]
  8. Multiplicity and regulation of genes encoding peptide transporters in Saccharomyces cerevisiae. Hauser, M., Narita, V., Donhardt, A.M., Naider, F., Becker, J.M. Mol. Membr. Biol. (2001) [Pubmed]
  9. Isolation and characterization of S. cerevisiae mutants deficient in amino acid-inducible peptide transport. Island, M.D., Perry, J.R., Naider, F., Becker, J.M. Curr. Genet. (1991) [Pubmed]
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