FUI1/YBL042C Summary Help

Standard Name FUI1 1
Systematic Name YBL042C
Feature Type ORF, Verified
Description High affinity uridine permease, localizes to the plasma membrane; also mediates low but significant transport of the cytotoxic nucleoside analog 5-fluorouridine; not involved in uracil transport; relative distribution to the vacuole increases upon DNA replication stress (2, 3, 4, 5 and see Summary Paragraph)
Name Description 5-FlUorourIdine resistance 1
Chromosomal Location
ChrII:140260 to 138341 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All FUI1 GO evidence and references
  View Computational GO annotations for FUI1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 12 genes
Classical genetics
Large-scale survey
28 total interaction(s) for 24 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 3
  • Affinity Capture-RNA: 1
  • PCA: 7
  • Protein-RNA: 1
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 10
  • Synthetic Growth Defect: 4

Expression Summary
Length (a.a.) 639
Molecular Weight (Da) 72,164
Isoelectric Point (pI) 7.47
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:140260 to 138341 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1920 140260..138341 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | TCDB | UniProtKB
Primary SGDIDS000000138

Fui1p is a uridine permease located in the plasma membrane. It has high affinity and selectivity for uridine (3, 1, 2), and does not transport uracil or allantoin into the cell (6, 2).

fui1 null mutants are viable, and are resistant to 5-fluorouridine, but do not grow on medium containing uridine as the sole source of pyrimidines (7, 2, 1). In a large-scale synthetic genetic array analysis, fui1 mutations also cause synthetic growth defects in combination with mutations in either LAS21, which encodes a plasma membrane protein involved in glycosylphosphatidylinositol synthesis, or RIC1, which encodes a protein involved in retrograde transport to the cis-Golgi network (8). Fui1p is able to transport uracil when it is overexpressed, and overexpression of Fui1p results in a decreased growth rate in the presence of uridine (2, 6).

Fui1p is degraded via ubiquitination, endocytosis, and then vacuolar degradation (9, 6). Uridine promotes Rsp5p-dependent ubiquitination of Fui1p at the plasma membrane, followed by its endocytosis and then vacuolar degradation (6). In cells being exposed to toxic levels of uridine, uridine is also able to direct Fui1p for early vacuolar degradation immediately after synthesis, without prior localization of Fui1p to the plasma membrane (6).

FUI1 belongs to a family of uracil/uridine/allantoin permease homologs, and has similarity to DAL4, FUR4, THI7, and YOR071C, and Schizosaccharomyces pombe fur4 (10, 11, 12, 2, 13, 14).

Last updated: 2005-12-14 Contact SGD

References cited on this page View Complete Literature Guide for FUI1
1) Jund R and Lacroute F  (1970) Genetic and physiological aspects of resistance to 5-fluoropyrimidines in Saccharomyces cerevisiae. J Bacteriol 102(3):607-15
2) Wagner R, et al.  (1998) The ORF YBL042 of Saccharomyces cerevisiae encodes a uridine permease. FEMS Microbiol Lett 159(1):69-75
3) Vickers MF, et al.  (2000) Nucleoside transporter proteins of Saccharomyces cerevisiae. Demonstration of a transporter (FUI1) with high uridine selectivity in plasma membranes and a transporter (FUN26) with broad nucleoside selectivity in intracellular membranes. J Biol Chem 275(34):25931-8
4) Zhang J, et al.  (2006) Characterization of the transport mechanism and permeant binding profile of the uridine permease Fui1p of Saccharomyces cerevisiae. J Biol Chem 281(38):28210-21
5) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
6) Blondel MO, et al.  (2004) Direct sorting of the yeast uracil permease to the endosomal system is controlled by uracil binding and Rsp5p-dependent ubiquitylation. Mol Biol Cell 15(2):883-95
7) Malagon F and Aguilera A  (1999) Construction and genetic analysis of S. cerevisiae deletants of six novel ORFs from chromosome II. Yeast 15(10B):955-61
8) Tong AH, et al.  (2004) Global mapping of the yeast genetic interaction network. Science 303(5659):808-13
9) Rotin D, et al.  (2000) Ubiquitination and endocytosis of plasma membrane proteins: role of Nedd4/Rsp5p family of ubiquitin-protein ligases. J Membr Biol 176(1):1-17
10) de Montigny J, et al.  (1998) The uracil permease of Schizosaccharomyces pombe: a representative of a family of 10 transmembrane helix transporter proteins of yeasts. Yeast 14(11):1051-9
11) De Wergifosse P, et al.  (1994) The sequence of a 22.4 kb DNA fragment from the left arm of yeast chromosome II reveals homologues to bacterial proline synthetase and murine alpha-adaptin, as well as a new permease and a DNA-binding protein. Yeast 10(11):1489-96
12) Marchal C, et al.  (1998) A PEST-like sequence mediates phosphorylation and efficient ubiquitination of yeast uracil permease. Mol Cell Biol 18(1):314-21
13) Nelissen B, et al.  (1995) Phylogenetic classification of the major superfamily of membrane transport facilitators, as deduced from yeast genome sequencing. FEBS Lett 377(2):232-6
14) Nelissen B, et al.  (1997) Classification of all putative permeases and other membrane plurispanners of the major facilitator superfamily encoded by the complete genome of Saccharomyces cerevisiae. FEMS Microbiol Rev 21(2):113-34