FLO1/YAR050W Summary Help

Standard Name FLO1
Systematic Name YAR050W
Alias FLO2 , FLO4
Feature Type ORF, Verified
Description Lectin-like protein involved in flocculation; cell wall protein that binds mannose chains on the surface of other cells, confers floc-forming ability that is chymotrypsin sensitive and heat resistant; FLO1 has a paralog, FLO5, that arose from a segmental duplication (1, 2, 3 and see Summary Paragraph)
Name Description FLOcculation
Chromosomal Location
ChrI:203403 to 208016 | ORF Map | GBrowse
Genetic position: 44 cM
Gene Ontology Annotations All FLO1 GO evidence and references
  View Computational GO annotations for FLO1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 3 genes
Classical genetics
Large-scale survey
16 total interaction(s) for 15 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 3

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 11
  • Positive Genetic: 1

Expression Summary
Length (a.a.) 1,537
Molecular Weight (Da) 160,667
Isoelectric Point (pI) 3.93
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrI:203403 to 208016 | ORF Map | GBrowse
Genetic position: 44 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1998-09-02
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..4614 203403..208016 2011-02-03 1998-09-02
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) | UniProtKB
Primary SGDIDS000000084

Flocculation, the calcium-dependent, non-sexual aggregation of yeast cells into 'flocs', is stimulated by nutrient limitation and is a process of great importance to the brewing characteristics of yeast strains (4). Characterization of flocculation characteristics has defined two classes of flocculation phenotypes. The FLO1-type is inhibited only by mannose sugars (5). The NewFLO-type, common in brewing strains, is inhibited by the sugars mannose, maltose, glucose, and sucrose, as well as by ammonium ions (5).

Genetic experiments defined three dominant flocculation genes, FLO1, FLO5, and FLO8, which are all in the FLO1-type phenotypic class 4. The FLO1 and FLO5 phenotypes could be distinguished by differences in sensitivity to heat or chymotrypsin. Floc-forming ability conferred by FLO1 is chymotrypsin-sensitive and heat-resistant, while floc-forming ability conferred by FLO5 is chymotrypsin-resistant but heat-labile 1. The FLO8 phenotype, however, turned out to be allelic with FLO1 6; this FLO8 is unrelated to FLO8/YER109C, which is a transcription factor 7.

Flo1p is a lectin-like cell-surface protein which aggregates cells into 'flocs' by binding to mannose sugar chains on the surfaces of other cells 2. Both the phenotypic characterization of FLO5 strains 5 and the sequence similarity between FLO5 and FLO1 6 suggest that Flo5p is also a mannose-binding lectin-like cell surface protein. Comparison of an Lg-FLO gene, cloned from a bottom-fermenting commercial yeast strain with the NewFLO phenotype, with the FLO1 gene demonstrates that the Lg-FLO gene is largely similar to FLO1, with some differences in the sugar binding site in the N-terminus of each protein 2.

Sequence analysis suggests that the flocculation genes are a multi-gene family localized to telomeric sequences, similarly to the SUC, MEL, and MAL gene families, all of which also encode characteristics important for brewing strains (4). In addition to FLO1 and FLO5, there are thought to be two more flocculation genes and three pseudogenes. The FLO9 gene (YAL063C) is 94% similar to the FLO1 gene and may be the source of a 4.2-kb transcript whose presence is not affected by deletions of FLO1 or FLO5. The FLO10 gene (YKR102W) is 58% similar to FLO1, but has 81.9% similarity in the N-terminus (4). Three presumed pseudogenes, YAL065C, YAR061W and YAR062W, and YHR213W have also been identified as fragmentary pieces with sequence similarity to FLO1 (4).

Last updated: 2004-02-09 Contact SGD

References cited on this page View Complete Literature Guide for FLO1
1) Hodgson JA, et al.  (1985) Discrimination by heat and proteinase treatments between flocculent phenotypes conferred on Saccharomyces cerevisiae by the genes FLO1 and FLO5. J Gen Microbiol 131(12):3219-27
2) Kobayashi O, et al.  (1998) Region of FLO1 proteins responsible for sugar recognition. J Bacteriol 180(24):6503-10
3) Katju V, et al.  (2009) Variation in gene duplicates with low synonymous divergence in Saccharomyces cerevisiae relative to Caenorhabditis elegans. Genome Biol 10(7):R75
4) Teunissen AW and Steensma HY  (1995) Review: the dominant flocculation genes of Saccharomyces cerevisiae constitute a new subtelomeric gene family. Yeast 11(11):1001-13
5) Stratford M  (1989) Evidence for two mechanisms of flocculation in Saccharomyces cerevisiae. Yeast 5 Spec No():S441-5
6) Teunissen AW, et al.  (1995) Localization of the dominant flocculation genes FLO5 and FLO8 of Saccharomyces cerevisiae. Yeast 11(8):735-45
7) Rupp S, et al.  (1999) MAP kinase and cAMP filamentation signaling pathways converge on the unusually large promoter of the yeast FLO11 gene. EMBO J 18(5):1257-69