LIPID MAPS Classification updates

(Revised on March 20th, 2017. See details below)

The LIPID MAPS consortium has developed a comprehensive classification, nomenclature, and chemical representation system for lipids. The details of the classification system first appeared in the May 2005 issue of the Journal of Lipid Research: Fahy, E., Subramaniam, S., Brown, H. A., Glass, C. K., Merrill, A. H., Jr., Murphy, R. C., Raetz, C. R., Russell, D. W., Seyama, Y., Shaw, W., Shimizu, T., Spener, F., van Meer, G., VanNieuwenhze, M. S., White, S. H., Witztum, J. L., and Dennis, E. A. A comprehensive classification system for lipids, J. Lipid Res.(2005) 46, 839-861. PubMed ID: 15722563.
Since then, a substantial number of updates and improvements have been made to the classification system,(described in the May 2009 issue of the Journal of Lipid Research:Fahy E, Subramaniam S, Murphy R, Nishijima M, Raetz C, Shimizu T, Spener F, van Meer G, Wakelam M and Dennis E.A.,Update of the LIPID MAPS comprehensive classification system for lipids. J. Lipid Res.. (2009) 50: p. S9-S14.PubMed ID:19098281.) and these are outlined below:

Overview of classification updates

  • Additional classes and subclasses
    In response to worldwide interest in the lipid classification system, the scope has been expanded to cover lipids from non-mammalian sources such as plants, bacteria, fungi, algae and marine organisms. In order to accomplish this, several new lipid classes have been added, such as fatty acyl glycosides, glycosyldiradylglycerols, various sterol skeletons. The polyketide category has also been revised comprehensively. Details of the changes are listed by category below.
  • Removal of classes based on lipid source
    In keeping with the theme of having a classification scheme dictated by molecular structure and function, the sterol lipid subclasses Phytosterols, Marine sterols and Fungal sterols were retired because these refer to the lipid source (marine) or biological kingdom (plants,fungi). It is possible to identify a particular sterol in more than one of these 3 sources. These subclasses have been replaced by a new set of subclasses based on the carbon skeleton of the sterol core structure (Ergosterols, Gorgosterols, Furostanols,etc.). The details are outlined under the Sterol lipids section below.
  • Adoption of existing natural products classification hierarchies for isoprenoids and polyketides
  • Whereas the focus of the LIPID MAPS consortium is mainly concerned with mammalian lipids, the natural products chemistry and medicinal chemistry literature describes tens of thousands of molecules which fall under the scope of lipids, based on their biosynthetic origin. In particular isoprenoids and polyketides from diverse sources such as plant, fungi, algae, bacteria and marine invertebrates and are well documented and have been reviewed and classified in detail. In particular, the Dictionary of Natural Products, a database available from Chapman & Hall/CRC (see website) has a classification hierarchy shown in this pdf document which covers polyketides and isoprenoids in depth. The LIPID MAPS classification system has now incorporated some of these hierarchies relevant to natural products, with a view to covering both mammalian and non-mammalian lipids comprehensively.
  • Expansion of classification levels
  • It was recognized that additional levels of granularity were required to classify certain types of lipids and that the current 3-level system of category/main class/sub class needed to be expanded. For example, in the Prenol lipids category the sesquiterpene(C 15) subclass contains approximately 90 known variants based on their carbon skeletons (Bisabolanes, Germacranes, etc.). A 4th level of detail has been added to the LIPID MAPS classifcation system in order to handle cases such as these.
  • Expansion of LM_ID identifier
    As a consequence of adding an extra level of classification detail, the length of the LM_ID identifier was lengthened from 12 characters to 14 in cases where a lipid defined with 4 levels of classification is being described. In this case, characters #9 and 10 specify the level-4 class . It should be emphasized that all lipids which do not require a 4th level of detail (i.e. the vast majority of them) still use a 12-digit LM_ID identifier.

    CharactersDescriptionExampleComments
    1-2Fixed "LM" designationLMAlways LM
    3-42-letter category codeFAOne of 8 categories
    5-62-digit class code03-
    7-82-digit subclass code02May be '00' (no subclass)
    9-102-digit class level-4 code02Only used for lipids with 4 class levels
    Last 4 digitsUnique 4-character identifier within subclass7312-

  • Changes to Glycerophospholipid abbreviations
    In response to several requests from knowledgeable lipid experts, the Glycerophospholipid abbreviation system has been changed to the more universally used PC/PE/PS/PA/PI system (replacing GPCho/GPEtn/GPSer/GPA/GPI). All glycerophospholipids in the LIPID MAPS structure database and LIPID MAPS standards database, as well as all the glycerophospholipids drawing tools and MS prediction tools have been updated to conform to this new abbreviation format. The details of the changes are shown in a table under the Glycerophospholipid lipids section below.
  • Use of expandable/collapsible menus on website
  • This is simply a cosmetic change in which there is an option to view the classification system of each lipid category as a top-level outline of main classes, and then click on the '+' icon of a main class of interest to view the corresponding sub class. This feature is convenient in the case of categories such as Glycerophospholipids and Prenol lipids which have large numbers of subclasses and/or 4th level classes. See the classification page to view this feature.

Details of classification updates (March 20th, 2017)

Fatty acyls [FA]

Added these subclasses to Octadecanoids [FA02] main class:
Phytoprostanes [FA0203]
Phytofurans [FA0204]
Octadeca-1,2-dioxolanes [FA0205]

Added these subclasses to Eicosanoids [FA03] main class:
Isofurans [FA0313]
Eicosa-1,2-dioxolanes [FA0315]
Resolvin Es [FA0314]

Added these subclasses to Docosanoids [FA04] main class:
Neuroprostanes [FA0401]
Neurofurans [FA0402]
Resolvin Ds [FA0403]
Docosa-1,2-dioxolanes [FA0406]
Protectins [FA0404]
Maresins [FA0405]
Other Docosanoids [FA0400]
(Previously, the docosanoids main class did not have subclasses)

Polyketides [PR]

Added this main class:
Phenolic lipids [PK15]

Added these subclasses to Phenolic lipids [PK15] main class:
Alkyl phenols and derivatives [PK1501]
Alkyl catechols and derivatives [PK1502]
Alkyl resorcinols and derivatives [PK1503]
Anacardic acids and derivatives [PK1504]
Alkyl hydroquinones and derivatives [PK1505]

 

Details of classification updates (July 14th, 2009)

Fatty acyls [FA]

Hydroxyeicosatrienoic acids [FA0305]
Hydroxyeicosatetraenoic acids [FA0306]
Hydroxyeicosapentaenoic acids [FA0307]

changed to:
Hydroxy/hydroperoxyeicosatrienoic acids [FA0305]
Hydroxy/hydroperoxyeicosatetraenoic acids [FA0306]
Hydroxy/hydroperoxyeicosapentaenoic acids [FA0307]
Clavulones [FA0312]
changed to:
Clavulones and derivatives [FA0312]

Added:
Other Eicosanoids [FA0300]

N-acyl amides [FA0802]
N-acyl ethanolamides (endocannabinoids) [FA0804]
changed to:
N-acyl amines [FA0802]
N-acyl ethanolamines (endocannabinoids) [FA0804]

Added:
Fatty acyl glycosides [FA13]
    Fatty acyl glycosides of mono- and disaccharides [FA1301]
    Sophorolipids [FA1302]
    Rhamnolipids [FA1303]
    Other Fatty acyl glycosides [FA1300]

 

Glycerolipids [GL]

Removed:
Alkylacylglycerols [GL0202]

Added:
1-alkyl,2-acylglycerols [GL0202]
1-acyl,2-alkylglycerols [GL0207]

Removed:
Monoacylglycerolglycosides [GL0104]
Monoalkylglycerolglycosides [GL0105]
Alkylacylglycerolglycosides [GL0206]
Dialkylglycerolglycosides [GL0207]

Added:
Glycosylmonoradylglycerols [GL04]
    Glycosylmonoacylglycerols [GL0401]
    Glycosylmonoalkylglycerols [GL0402]
Glycosyldiradylglycerols [GL05]
    Glycosyldiacylglycerols [GL0501]
    Glycosylalkylacylglycerols [GL0502]
    Glycosyldialkylglycerols [GL0503]

Positional isomers specifications in LIPID MAPS abbreviations for glycerolipids
For Diradylglycerols and Triradylglycerols, it is not always possible to experimentally determine the exact position of radyl groups on the glycerol group. For Diradylglycerols with two different radyl groups, two different structural isomers exist. For Triradylglycerols with three different radyl groups, six different isomers exist.

Instead of drawing all possible structural isomers explicitly for Diradylglycerols and Triradylglycerols, the LIPID MAPS abbreviation scheme supports the isomeric specification. A suffix containing 'iso' along with the number of possible isomers is appended to the abbreviation (e.g. [iso2],[iso6]) and a single unique LM_ID is assigned. The structure assigned to the LM_ID corresponds to the radyl substitution shown in the abbreviation. An option is provided to display the other isomers in the group.

The [rac] designation refers to racemic mixtures due to substitution at the sn1 and sn3 positions of glycerol.

Examples:
Abbreviation: DG(16:0/16:1(9Z)/0:0)[iso2]; LM_ID: LMGL02010010; Systematic name: 1-hexadecanoyl-2-(9Z-hexadecenoyl)-sn-glycerol
Abbreviation: TG(16:1(9Z)/17:0/17:0)[iso3]; LM_ID: LMGL03010027; Systematic name: 1-(9Z-hexadecenoyl)-2,3-diheptadecanoyl-sn-glycerol
Abbreviation: TG(16:0/17:0/17:1(9Z))[iso6]; LM_ID: LMGL03010028; Systematic name: 1-hexadecanoyl-2-heptadecanoyl-3-(9Z-heptadecenoyl)-sn-glycerol.

 

Glycerophospholipids [GP]

Added:
1-acyl,2-alkylglycerophosphocholines [GP0108]

1-alkyl glycerophosphocholines [GP0106]
changed to:
Monoalkylglycerophosphocholines [GP0106]

Added:
1-acyl,2-alkylglycerophosphoethanolamines [GP0208]

1-alkyl glycerophosphoethanolamines [GP0206]
changed to:
Monoalkylglycerophosphoethanolamines [GP0206]

1-alkyl glycerophosphoethanoserines [GP0306]
changed to:
Monoalkylglycerophosphoserines [GP0306]

1-alkyl glycerophosphoglycerols [GP0406]
changed to:
Monoalkylglycerophosphoglycerols [GP0406]

1-alkyl glycerophosphoethanophosphates [GP0506]
changed to:
Monoalkylglycerophosphophosphates [GP0506]

1-alkyl glycerophosphoethanoinositols [GP0606]
changed to:
Monoalkylglycerophosphoinositols [GP0606]

1-alkyl glycerophosphoethanoinositol monophosphates [GP0706]
changed to:
Monoalkylglycerophosphoinositol monophosphates [GP0706]

1-alkyl glycerophosphoethanoinositol bisphosphates [GP0805]
changed to:
Monoalkylglycerophosphoinositol bisphosphates [GP0805]

1-alkyl glycerophosphoethanoinositol trisphosphates [GP0905]
changed to:
Monoalkylglycerophosphoinositol trisphosphates [GP0905]

1-alkyl glycerophosphates [GP1006]
changed to:
Monoalkylglycerophosphates [GP1006]

1-alkyl glycerophosphoethanophosphates [GP0506]
changed to:
Monoalkylglycerophosphophosphates [GP0506]

Added:
Dialkylglycerophosphoglycerophosphodiradylglycerols [GP1212]
Dialkylglycerophosphoglycerophosphomonoradylglycerols [GP1213]

1-alkyl glycerophosphoglycerophosphodiradylglycerols [GP1208]
1-alkyl glycerophosphoglycerophosphomonoradylglycerols [GP1209]
changed to:
Monoalkylglycerophosphoglycerophosphodiradylglycerols [GP1208]
Monoalkylglycerophosphoglycerophosphomonoradylglycerols [GP1209]

CDP-1-alkyl glycerols [GP0506]
changed to:
CDP-Monoalkylglycerols [GP1306]

Removed:
Glycerophosphoglucose lipids [GP14]     Diacylglycerophosphoglucose lipids [GP1401]
    1-alkyl,2-acylglycerophosphoglucose lipids [GP1402]
    1Z-alkenyl,2-acylglycerophosphoglucose lipids [GP1403]
    Monoacylglycerophosphoglucose lipids [GP1404]
    1-alkyl glycerophosphoglucose lipids [GP1405]
    1Z-alkenylglycerophosphoglucose lipids [GP1406

Added:
Glycosylglycerophospholipids [GP14]
    Diacylglycosylglycerophospholipids [GP1401]
    1-alkyl,2-acylglycosylglycerophospholipids [GP1402]
    1Z-alkenyl,2-acylglycosylglycerophospholipids [GP1403]
    Dialkylglycosylglycerophospholipids [GP1407]
    Monoacylglycosylglycerophospholipids [GP1404]
    Monoalkylglycosylglycerophospholipids [GP1405]
    1Z-alkenylglycosylglycerophospholipids [GP1406]

1-alkyl glycerophosphoinositolglycans [GP1505]
changed to:
Monoalkylglycerophosphoinositolglycans [GP1505]

1-alkyl glycerophosphonocholines [GP1606]
changed to:
Monoalkylglycerophosphonocholines [GP1606]

1-alkyl glycerophosphonoethanolamines [GP1706]
changed to:
Monoalkylglycerophosphonoethanolamines [GP1706]

Changes in LIPID MAPS abbreviations for glycerophospholipids

ClassPreviousNew
GlycerophosphocholinesGPChoPC
GlycerophosphoethanolaminesGPEtnPE
GlycerophosphoserinesGPSerPS
GlycerophosphoglycerolsGPGroPG
GlycerophosphoglycerophosphatesGPGroPPGP
GlycerophosphoinositolsGPInsPI
Glycerophosphoinositol monophosphatesGPInsPPIP
Glycerophosphoinositol bis-phosphatesGPInsP2PIP2
Glycerophosphoinositol tris-phosphatesGPInsP3PIP3
GlycerophosphatesGPAPA
GlyceropyrophosphatesGPPPPA
GlycerophosphoglycerophosphoglycerolsCLCL
CDP-glycerolsGCDPCDP-DG
Glycosylglycerophospholipids [glycan]-GP[glycan]-GP
Glycerophosphoinositolglycans[glycan]-GPIns[glycan]-PI
GlycerophosphonocholinesGPnChoPnC
GlycerophosphonoethanolaminesGPnEtnPnE

Stereochemistry specifications in LIPID MAPS abbreviations for glycerophospholipids
The LIPID MAPS glycerophospholipid abbreviations (PC, PE, etc.) are used here to refer to species with one or two radyl side-chains where the structures of the side chains are indicated within parentheses in the 'Headgroup(sn1/sn2)' format (e.g. PC(16:0/18:1(9Z)). By default, R stereochemistry at the C2 carbon of glycerol and attachment of the headgroup at the sn3 position.

For molecules with opposite (S) stereochemistry at C2 of the glycerol group and attachment of the headgroup at the sn1 position, the stereochemistry specification of [S] is appended to the abbreviation. The 'Headgroup(sn3/sn2)' abbreviation format is used.

For molecules with unknown stereochemistry at the C2 carbon of the glycerol group, the stereochemistry specification of [U] is appended to the abbreviation and the structure is drawn with C2 stereochemistry unspecified. For example: Abbreviation - PC(16:0/18:1(9E)[U]); LMID - LMGP01010582; Systematic name - 1-hexadecanoyl-2-(9E-octadecenoyl)-sn-glycero-3-phosphocholine.

 

Sphingolipids [SP]

No changes

 

Sterol lipids [ST]

Removed:
Phytosterols and derivatives [ST0103]
Marine sterols and derivatives [ST0104]
Fungal sterols and derivatives [ST0105]

Added:
Ergosterols and C24-methyl derivatives [ST0103]
Stigmasterols and C24-ethyl derivatives [ST0104]
C24-propyl sterols and derivatives [ST0105]
Gorgosterols and derivatives [ST0106]
Furostanols and derivatives [ST0107]
Spirostanols and derivatives [ST0108]
Furospirostanols and derivatives [ST0109]
Cycloartanols and derivatives [ST0110]
Calysterols and derivatives [ST0111]
Cardanolides and derivatives [ST0112]
Bufanolides and derivatives [ST0113]
Brassinolides and derivatives [ST0114]
Solanidines and alkaloid derivatives [ST0115]

Added:
Vitamin D4 and derivatives [ST0303]
Vitamin D5 and derivatives [ST0304]
Vitamin D6 and derivatives [ST0305]
Vitamin D7 and derivatives [ST0306]

Added:
C22 bile acids, alcohols, and derivatives [ST0405]
C23 bile acids, alcohols, and derivatives [ST0406]
C25 bile acids, alcohols, and derivatives [ST0407]
C29 bile acids, alcohols, and derivatives [ST0408]

Removed:
Hopanoids [ST06] (now classified under Prenol lipids)

 

Prenol Lipids [PR]

Added:
Extra level of subclassification to C10 isoprenoids (monoterpenes) [PR0102]
Acyclic monoterpenoids [PR010201]
etc., etc.

Extra level of subclassification to C15 isoprenoids (sesquiterpenes) [PR0103]
Acyclic farnesane sesquiterpenoids [PR010301]
etc., etc.

Extra level of subclassification to C20 isoprenoids (diterpenes) [PR0104]
Acyclic diterpenoids [PR010401]
etc., etc.

Extra level of subclassification to C25 isoprenoids (sesterterpenes) [PR0105]
Acyclic triterpenoids [PR010501]
etc., etc.

Extra level of subclassification to C30 isoprenoids (triterpenes) [PR0106]
Acyclic triterpenoids [PR010601]
etc., etc.

Added:
Retinoids [PR0109]

Added:
Hopanoids [PR04] (previously classified under Sterol lipids)

 

Saccharolipids [SL]

Added:
Other acyl sugars [SL05]

 

Polyketides [PR]

(This category was completely revised)

Removed:
Macrolide polyketides [PK01]
Aromatic polyketides [PK02]
Non-ribosomal peptide/polyketide hybrids [PK03]
Other [PK00]

Added:
Linear polyketides [PK01]
Halogenated acetogenins [PK02]
Annonaceae acetogenins [PK03]
Macrolides and lactone polyketides [PK04]
Ansamycins and related polyketides [PK05]
Polyenes [PK06]
Linear tetracyclines [PK07]
Angucyclines [PK08]
Polyether antibiotics [PK09]
Aflatoxins and related substances [PK10]
Cytochalasins [PK11]
Flavonoids [PK12]
   Various subclasses
Aromatic polyketides [PK13]
   Various subclasses
Non-ribosomal peptide/polyketide hybrids [PK14]
Other Polyketides [PK00]

 

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