FAS2/YPL231W Summary Help

Standard Name FAS2 1
Systematic Name YPL231W
Feature Type ORF, Verified
Description Alpha subunit of fatty acid synthetase; complex catalyzes the synthesis of long-chain saturated fatty acids; contains the acyl-carrier protein domain and beta-ketoacyl reductase, beta-ketoacyl synthase and self-pantetheinylation activities (2, 3, 4 and see Summary Paragraph)
Name Description Fatty Acid Synthetase
Chromosomal Location
ChrXVI:108652 to 114315 | ORF Map | GBrowse
Genetic position: -125 cM
Gene Ontology Annotations All FAS2 GO evidence and references
  View Computational GO annotations for FAS2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 11 genes
Classical genetics
gain of function
Large-scale survey
reduction of function
64 total interaction(s) for 48 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 35
  • Affinity Capture-RNA: 4
  • Affinity Capture-Western: 2
  • Co-crystal Structure: 1
  • Co-purification: 1
  • PCA: 2
  • Reconstituted Complex: 1

Genetic Interactions
  • Negative Genetic: 12
  • Phenotypic Enhancement: 2
  • Positive Genetic: 3
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 1,887
Molecular Weight (Da) 206,945
Isoelectric Point (pI) 5.21
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXVI:108652 to 114315 | ORF Map | GBrowse
Genetic position: -125 cM
Last Update Coordinates: 1996-07-31 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..5664 108652..114315 1996-07-31 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 SGDIDS000006152

Fatty acids are essential components of eukaryotic and bacterial (but not archaeal) cells, where they are used in membrane synthesis, energy storage and protein modification. Most cells are capable of synthesizing, long chain saturated fatty acids de novo, using acetyl-CoA as a starting substrate. Fatty acid biosynthesis is essentially the same across organisms. In an iterative process, the growing fatty acid chain is gradually extended, two carbons at a time, until the final length is achieved. Each addition requires seven different catalytic activities as well as a pantetheinylated acyl-carrier protein, to which the growing fatty acid chain is attached (see fatty acid biosynthesis pathways: initial steps and elongation). In S. cerevisiae, palmitoleic (C16) and oleic (C18) acyl-CoAs are the most common products of this process. Although the biochemistry is similar across phylogeny, the physical organization of the catalytic sites varies between organisms. Plants, mitochondria and most bacteria have type II Fatty Acid Synthase (FAS II) systems, where each enzymatic activity is encoded by an individual, disassociated protein. Fungi, animals and some bacteria have type I Fatty Acid Synthase (FAS I) systems involving complexes of multifunctional proteins. In humans, for example, only the enzyme catalyzing the first step in fatty acid synthesis (the formation of malonyl-CoA by acetyl-CoA carboxylase, EC: is a separate protein; all other activities are contained within a single polypeptide, ACSL1, which forms an X-shaped homodimer complex (reviewed in 5, 6, 7, 8, 9).

In S. cerevisiae, as in humans, only the acetyl-CoA carboxylase activity (Acc1p) is separate. In contrast to humans, however, the other activities are distributed between two proteins, Fas1p and Fas2p, the beta and alpha subunits of a large, barrel-shaped complex containing 6 copies of each protein (alpha6beta6) (10, 11). Together, the six Fas1p and six Fas2p subunits form six independent reaction centers, each containing all enzyme activities required for synthesizing long chain fatty acids from acetyl- and malony-CoA (12, 13, and references therein). FAS1 encodes four independent enzymatic functions: acetyltransferase (EC:, enoyl reductase (EC:, dehydratase (EC:, and malonyl/palmitoyl-transferase (EC: (14, 15, 16, 17). FAS2 encodes the acyl-carrier protein domain and three independent enzymatic functions: 3-ketoreductase (EC:, 3-ketosynthase (EC: and phosphopantetheinyl transferase (EC: (14, 2, 3). This last enzymatic activity is not part of fatty acid biosynthesis, but rather is responsible for the pantetheinylation of the acyl-carrier protein domain (3 and references therein). This post-translational modification is essential for FAS I activity and is thought to allow movement of the growing fatty acid chain between the different catalytic sites in each reaction center. In humans, the phosphopantetheinyl transferase activity is catalyzed by a separate enzyme that is disassociated from the FAS I complex, AASDHPPT (9, 18 and references therein).

As "housekeeping" genes, FAS1 and FAS2 are constitutively activated by general transcription factors Rap1p, Abf1p, and Reb1p (19). Both FAS1 and FAS2 are further activated by the inositol/choline-responsive transcription factor heteroduplex, Ino2p-Ino4p (20, 21). In addition, Fas1p and Fas2p stoichiometry appears to be insured by a regulatory mechanism in which FAS1 protein controls FAS2 mRNA levels (22).

Last updated: 2010-04-24 Contact SGD

References cited on this page View Complete Literature Guide for FAS2
1) Schweizer, E.  (1989) Personal Communication, Mortimer Map Edition 10
2) Mohamed AH, et al.  (1988) Primary structure of the multifunctional alpha subunit protein of yeast fatty acid synthase derived from FAS2 gene sequence. J Biol Chem 263(25):12315-25
3) Fichtlscherer F, et al.  (2000) A novel function of yeast fatty acid synthase. Subunit alpha is capable of self-pantetheinylation. Eur J Biochem 267(9):2666-71
4) Reinders J, et al.  (2007) Profiling phosphoproteins of yeast mitochondria reveals a role of phosphorylation in assembly of the ATP synthase. Mol Cell Proteomics 6(11):1896-906
5) Lynen F  (1980) On the structure of fatty acid synthetase of yeast. Eur J Biochem 112(3):431-42
6) Schweizer E and Hofmann J  (2004) Microbial type I fatty acid synthases (FAS): major players in a network of cellular FAS systems. Microbiol Mol Biol Rev 68(3):501-17, table of contents
7) Tehlivets O, et al.  (2007) Fatty acid synthesis and elongation in yeast. Biochim Biophys Acta 1771(3):255-70
8) Kolter T  (2007) The Fatty Acid Factory of Yeasts. Angew Chem Int Ed Engl 46(36):6772-6775
9) Leibundgut M, et al.  (2008) The multienzyme architecture of eukaryotic fatty acid synthases. Curr Opin Struct Biol 18(6):714-25
10) Wieland F, et al.  (1978) Distribution of yeast fatty acid synthetase subunits: three-dimensional model of the enzyme. Proc Natl Acad Sci U S A 75(12):5792-6
11) Kolodziej SJ, et al.  (1996) Structure-function relationships of the Saccharomyces cerevisiae fatty acid synthase. Three-dimensional structure. J Biol Chem 271(45):28422-9
12) Leibundgut M, et al.  (2007) Structural basis for substrate delivery by acyl carrier protein in the yeast fatty acid synthase. Science 316(5822):288-90
13) Lomakin IB, et al.  (2007) The crystal structure of yeast fatty acid synthase, a cellular machine with eight active sites working together. Cell 129(2):319-32
14) Stoops JK and Wakil SJ  (1978) The isolation of the two subunits of yeast fatty acid synthetase. Biochem Biophys Res Commun 84(1):225-31
15) Schweizer M, et al.  (1986) The pentafunctional FAS1 gene of yeast: its nucleotide sequence and order of the catalytic domains. Mol Gen Genet 203(3):479-86
16) Wieland F, et al.  (1979) Studies on the multi-enzyme complex of yeast fatty-acid synthetase. Reversible dissociation and isolation of two polypeptide chains. Eur J Biochem 94(1):189-97
17) Kottig H, et al.  (1991) The pentafunctional FAS1 genes of Saccharomyces cerevisiae and Yarrowia lipolytica are co-linear and considerably longer than previously estimated. Mol Gen Genet 226(1-2):310-4
18) Bunkoczi G, et al.  (2007) Mechanism and substrate recognition of human holo ACP synthase. Chem Biol 14(11):1243-53
19) Schuller HJ, et al.  (1994) Importance of general regulatory factors Rap1p, Abf1p and Reb1p for the activation of yeast fatty acid synthase genes FAS1 and FAS2. Eur J Biochem 225(1):213-22
20) Schuller HJ, et al.  (1992) Regulatory gene INO4 of yeast phospholipid biosynthesis is positively autoregulated and functions as a transactivator of fatty acid synthase genes FAS1 and FAS2 from Saccharomyces cerevisiae. Nucleic Acids Res 20(22):5955-61
21) Schwank S, et al.  (1995) Yeast transcriptional activator INO2 interacts as an Ino2p/Ino4p basic helix-loop-helix heteromeric complex with the inositol/choline-responsive element necessary for expression of phospholipid biosynthetic genes in Saccharomyces cerevisiae. Nucleic Acids Res 23(2):230-7
22) Wenz P, et al.  (2001) A downstream regulatory element located within the coding sequence mediates autoregulated expression of the yeast fatty acid synthase gene FAS2 by the FAS1 gene product. Nucleic Acids Res 29(22):4625-32