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Entry version 229 (07 Apr 2021)
Sequence version 3 (24 Nov 2009)
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Fatty acid synthase



Homo sapiens (Human)
Reviewed-Annotation score:

Annotation score:5 out of 5

<p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB entry or proteome. This score <strong>cannot</strong> be used as a measure of the accuracy of the annotation as we cannot define the 'correct annotation' for any given protein.<p><a href='/help/annotation_score' target='_top'>More...</a></p>
-Experimental evidence at protein leveli <p>This indicates the type of evidence that supports the existence of the protein. Note that the 'protein existence' evidence does not give information on the accuracy or correctness of the sequence(s) displayed.<p><a href='/help/protein_existence' target='_top'>More...</a></p>

<p>This section provides any useful information about the protein, mostly biological knowledge.<p><a href='/help/function_section' target='_top'>More...</a></p>Functioni

Fatty acid synthetase is a multifunctional enzyme that catalyzes the de novo biosynthesis of long-chain saturated fatty acids starting from acetyl-CoA and malonyl-CoA in the presence of NADPH. This multifunctional protein contains 7 catalytic activities and a site for the binding of the prosthetic group 4'-phosphopantetheine of the acyl carrier protein ([ACP]) domain.6 Publications


The relatively low beta-ketoacyl synthase activity may be attributable to the low 4'-phosphopantetheine content of the protein.

<p>This subsection of the <a href="">Function</a> section describes the catalytic activity of an enzyme, i.e. a chemical reaction that the enzyme catalyzes.<p><a href='/help/catalytic_activity' target='_top'>More...</a></p>Catalytic activityi

<p>This subsection of the <a href="">Function</a> section describes regulatory mechanisms for enzymes, transporters or microbial transcription factors, and reports the components which regulate (by activation or inhibition) the reaction.<p><a href='/help/activity_regulation' target='_top'>More...</a></p>Activity regulationi

Activated by S-nitrosylation which promotes enzyme dimerization (PubMed:26851298). Cerulenin, a potent non-competitive pharmacological inhibitor of FAS, binds covalently to the active site of the condensing enzyme region, inactivating a key enzyme step in fatty acid synthesis (PubMed:16969344).2 Publications

<p>This subsection of the 'Function' section describes biophysical and chemical properties, such as maximal absorption, kinetic parameters, pH dependence, redox potentials and temperature dependence.<p><a href='/help/biophysicochemical_properties' target='_top'>More...</a></p>Kineticsi

  1. KM=8 µM for acetyl-CoA1 Publication
  2. KM=20 µM for malonyl-CoA1 Publication
  3. KM=25 µM for NADPH1 Publication
  4. KM=4 µM for butanoyl-CoA1 Publication
  5. KM=7 µM for acetyl-CoA1 Publication
  6. KM=6 µM for malonyl-CoA1 Publication
  7. KM=5 µM for NADPH1 Publication
  1. Vmax=29.6 nmol/min/mg enzyme for the incorporation of acetyl-CoA into fatty acids1 Publication
  2. Vmax=220.6 nmol/min/mg enzyme for the incorporation of malonyl-CoA into fatty acids1 Publication
  3. Vmax=462 nmol/min/mg enzyme for the oxidation of NADPH1 Publication
  4. Vmax=440 nmol/min/mg enzyme for the oxidation of NADPH (at pH 7.0)1 Publication

pH dependencei

Optimum pH is 6.5 to 6.7.1 Publication

<p>This subsection of the <a href="">'Function'</a> section describes the metabolic pathway(s) associated with a protein.<p><a href='/help/pathway' target='_top'>More...</a></p>Pathwayi: fatty acid biosynthesis

This protein is involved in the pathway fatty acid biosynthesis, which is part of Lipid metabolism.3 Publications
View all proteins of this organism that are known to be involved in the pathway fatty acid biosynthesis and in Lipid metabolism.


Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="">Function</a> section is used for enzymes and indicates the residues directly involved in catalysis.<p><a href='/help/act_site' target='_top'>More...</a></p>Active sitei161For beta-ketoacyl synthase activityPROSITE-ProRule annotation1
Active sitei581For malonyltransferase activityPROSITE-ProRule annotation1
<p>This subsection of the <a href="">Function</a> section describes the interaction between a single amino acid and another chemical entity. Priority is given to the annotation of physiological ligands.<p><a href='/help/binding' target='_top'>More...</a></p>Binding sitei671Acyl-CoABy similarity1
Binding sitei773Acyl-CoABy similarity1
Active sitei878For beta-hydroxyacyl dehydratase activityPROSITE-ProRule annotation1
Active sitei2308For thioesterase activityPROSITE-ProRule annotation1 Publication1
Active sitei2481For thioesterase activityPROSITE-ProRule annotation1


Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="">Function</a> section describes a region in the protein which binds nucleotide phosphates. It always involves more than one amino acid and includes all residues involved in nucleotide-binding.<p><a href='/help/np_bind' target='_top'>More...</a></p>Nucleotide bindingi1671 – 1688NADP; for enoyl reductase activityBy similarityAdd BLAST18
Nucleotide bindingi1886 – 1901NADP; for ketoreductase activityBy similarityAdd BLAST16

<p>The <a href="">Gene Ontology (GO)</a> project provides a set of hierarchical controlled vocabulary split into 3 categories:<p><a href='/help/gene_ontology' target='_top'>More...</a></p>GO - Molecular functioni

GO - Biological processi

<p>UniProtKB Keywords constitute a <a href="">controlled vocabulary</a> with a hierarchical structure. Keywords summarise the content of a UniProtKB entry and facilitate the search for proteins of interest.<p><a href='/help/keywords' target='_top'>More...</a></p>Keywordsi

Molecular functionHydrolase, Lyase, Multifunctional enzyme, Oxidoreductase, Transferase
Biological processFatty acid biosynthesis, Fatty acid metabolism, Lipid biosynthesis, Lipid metabolism
LigandNAD, NADP, Pyridoxal phosphate

Enzyme and pathway databases

BioCyc Collection of Pathway/Genome Databases


BRENDA Comprehensive Enzyme Information System

BRENDAi, 2681

Pathway Commons web resource for biological pathway data


Reactome - a knowledgebase of biological pathways and processes

R-HSA-163765, ChREBP activates metabolic gene expression
R-HSA-199220, Vitamin B5 (pantothenate) metabolism
R-HSA-2426168, Activation of gene expression by SREBF (SREBP)
R-HSA-75105, Fatty acyl-CoA biosynthesis
R-HSA-9029558, NR1H2 & NR1H3 regulate gene expression linked to lipogenesis

SABIO-RK: Biochemical Reaction Kinetics Database


SIGNOR Signaling Network Open Resource


UniPathway: a resource for the exploration and annotation of metabolic pathways


Protein family/group databases

ESTHER database of the Alpha/Beta-hydrolase fold superfamily of proteins

human-FASN, Thioesterase

Chemistry databases

SwissLipids knowledge resource for lipid biology


<p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence.<p><a href='/help/names_and_taxonomy_section' target='_top'>More...</a></p>Names & Taxonomyi

<p>This subsection of the <a href="">Names and taxonomy</a> section provides an exhaustive list of all names of the protein, from commonly used to obsolete, to allow unambiguous identification of a protein.<p><a href='/help/protein_names' target='_top'>More...</a></p>Protein namesi
Recommended name:
Fatty acid synthase (EC: Publications)
Alternative name(s):
Type I fatty acid synthase
Including the following 7 domains:
[Acyl-carrier-protein] S-acetyltransferase (EC: Publications)
[Acyl-carrier-protein] S-malonyltransferase (EC: Publications)
3-oxoacyl-[acyl-carrier-protein] synthase (EC: Publications