PRO3/YER023W Summary Help

Standard Name PRO3
Systematic Name YER023W
Alias ORE2 1
Feature Type ORF, Verified
Description Delta 1-pyrroline-5-carboxylate reductase; catalyzes the last step in proline biosynthesis (2, 3 and see Summary Paragraph)
Name Description PROline requiring
Chromosomal Location
ChrV:201076 to 201936 | ORF Map | GBrowse
Genetic position: 23 cM
Gene Ontology Annotations All PRO3 GO evidence and references
  View Computational GO annotations for PRO3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 3 genes
Classical genetics
Large-scale survey
reduction of function
45 total interaction(s) for 34 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 16
  • Affinity Capture-RNA: 4
  • Biochemical Activity: 1
  • PCA: 6
  • Reconstituted Complex: 1
  • Two-hybrid: 5

Genetic Interactions
  • Phenotypic Suppression: 1
  • Synthetic Growth Defect: 4
  • Synthetic Lethality: 5
  • Synthetic Rescue: 2

Expression Summary
Length (a.a.) 286
Molecular Weight (Da) 30,132
Isoelectric Point (pI) 5.29
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrV:201076 to 201936 | ORF Map | GBrowse
This feature contains embedded feature(s): YER023C-A
Genetic position: 23 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..861 201076..201936 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000825

Proline is a member of the glutamine family of amino acids, whose biosynthesis depends on the carbon skeleton of glutamic acid. Proline biosynthesis, shown here, occurs in the cytosol and begins with activation of glutamate, by the Pro1p gamma-glutamyl kinase (EC, to form glutamate-5-phosphate (4, 3). This unstable intermediate is subsequently converted to glutamate semialdehyde by the gamma-glutamyl phosphate reductase (EC Pro2p (4, 3). Glutamate semialdehyde spontaneously cyclizes to form delta 1-pyrroline-5-carboxylate (P5C) (4), which is then converted to proline by Pro3p, a P5C reductase (EC (4, 2). In S. cerevisiae, the P5C reductase enzyme also catalyzes the fourth step in arginine degradation (5). Since these two pathways converge at this step, the requirement for proline in pro1 and pro2 mutant cells can be satisfied by arginine. In contrast, pro3 mutants require the addition of proline for growth (3). A unique property of all the pro mutant strains is that they cannot grow on standard YPD rich media. (3).

In addition to proline auxotrophy, Pro3p deficiency results in a temperature-sensitive phenotype in which cells arrest in the G1 phase of the cell cycle (1). The PRO3 gene appears to be constitutively expressed and under no form of transcriptional regulation (2).

Last updated: 2005-09-21 Contact SGD

References cited on this page View Complete Literature Guide for PRO3
1) Neuville P and Aigle M  (1992) ore2, a mutation affecting proline biosynthesis in the yeast Saccharomyces cerevisiae, leads to a cdc phenotype. Mol Gen Genet 234(2):193-200
2) Brandriss MC and Falvey DA  (1992) Proline biosynthesis in Saccharomyces cerevisiae: analysis of the PRO3 gene, which encodes delta 1-pyrroline-5-carboxylate reductase. J Bacteriol 174(11):3782-8
3) Tomenchok DM and Brandriss MC  (1987) Gene-enzyme relationships in the proline biosynthetic pathway of Saccharomyces cerevisiae. J Bacteriol 169(12):5364-72
4) Brandriss MC  (1979) Isolation and preliminary characterization of Saccharomyces cerevisiae proline auxotrophs. J Bacteriol 138(3):816-22
5) Brandriss MC and Magasanik B  (1980) Proline: an essential intermediate in arginine degradation in Saccharomyces cerevisiae. J Bacteriol 143(3):1403-10