Symbol Nomenclature for Glycans (SNFG)

Standardization in drawing glycan structures is essential for efficient communication. The tools and methodology illustrated here have become widely accepted by the scientific community. Use of these symbols to represent monosaccharides is now strongly recommended for all manuscripts submitted to major journals and other publications.

Citation: Symbol Nomenclature for Graphical Representation of Glycans, Glycobiology 25: 1323-1324, 2015. Citation link (PMID 26543186).

History of the SNFG

The SNFG Discussion Group (July 2018)

Organizations and Publications Adopting SNFG

Software tools supporting SNFG

1. 3D-Symbol Nomenclature for Glycans (3D-SNFG): Create 3D atomic models of glycans
2. DrawGlycan SNFG: Convert IUPAC input strings to sketches of glycans and glycopeptides
3. GlycanBuilder2-SNFG: GlycanBuilder updated to handle SNFG

Symbol Nomenclature

Downloadable files: Drawing format | Presentation/Slide format | Notes | Examples

Hover over Symbol with pointer to see the monosaccharide name. Click on a symbol to link to the corresponding PubChem entry. Symbols can also be copied with embedded links from the table using right/control-click or highlight-copy (highlight a symbol, then control-c [on pc], or command⌘-c [on mac]). However links may not copy in some browsers. Symbols with embedded PubChem URLs are therefore also available in the presentation/slide format attachments (see links above the table).

Table 1. Monosaccharide symbol nomenclature

SHAPE	White (Generic)	Blue	Green	Yellow	Orange	Pink	Purple	Light Blue	Brown	Red
Filled Circle	Hexose	Glc	Man	Gal	Gul	Alt	All	Tal	Ido
Filled Square	HexNAc	GlcNAc	ManNAc	GalNAc	GulNAc	AltNAc	AllNAc	TalNAc	IdoNAc
Crossed Square	Hexosamine	GlcN	ManN	GalN	GulN	AltN	AllN	TalN	IdoN
Divided Diamond	Hexuronate	GlcA	ManA	GalA	GulA	AltA	AllA	TalA	IdoA
Filled Triangle	Deoxyhexose	Qui	Rha		6dGul	6dAlt		6dTal		Fuc
Divided Triangle	DeoxyhexNAc	QuiNAc	RhaNAc			6dAltNAc		6dTalNAc		FucNAc
Flat Rectangle	Di-deoxyhexose	Oli	Tyv		Abe	Par	Dig	Col
Filled Star	Pentose		Ara	Lyx	Xyl	Rib
Filled Diamond	Deoxynonulosonate		Kdn				Neu5Ac	Neu5Gc	Neu	Sia
Flat Diamond	Di-deoxynonulosonate		Pse	Leg		Aci		4eLeg
Flat Hexagon	Unknown	Bac	LDmanHep	Kdo	Dha	DDmanHep	MurNAc	MurNGc	Mur
Pentagon	Assigned	Api	Fru	Tag	Sor	Psi

Notes

1. Each symbol represents a specific monosaccharide or class of monosaccharides found in nature.
2. Assigned symbols are shown in this Appendix to the Third Edition of Essentials of Glycobiology.
3. Passing the tooltip/pointer over a symbol in the table at the NCBI website will show its full name.
4. Clicking on an assigned symbol will link to the corresponding entry in PubChem. Full symbol sets are also available as downloadable files (see note 25 below).
5. To ensure harmony with prior publications, minimal changes were made to the Second Edition symbol set (Figure 1.5 in the Second Edition), but conversion to black and white is no longer possible.
6. Shapes and colors are completely consistent with stereochemistry only for hexoses, hexosamines, N-acetylhexosamines, hexuronates, and pentoses.
7. Shapes only are consistent for deoxyhexoses, deoxy-N-acetylhexosamines , dideoxyhexoses, and nonulosonates.
8. A symbol encodes a defined monosaccharide (including D or L) independent of rotation or mirroring. Avoid rotations if possible.
9. The horizontally divided diamonds for IdoA and AltA are inverted, to indicate the commoner L-forms.
10. White symbols based on the standard shapes can be used to designate monosaccharides with unknown/undefined stereochemistry (e.g., a white circle can designate a hexose, type not defined, or a white diamond, any deoxynonulosonic acid). A red diamond can be used for Sia (sialic acid, type unknown, whether Neu5Gc or Neu5Ac, or any of the other >50 forms known to date).
11. Colored pentagons and flat hexagons are used for some other monosaccharides that are common in nature. The hexagon is flat because it might otherwise look similar to a circle or square.
12. Monosaccharides not represented in this table can be shown with a white pentagon and a letter inside and should be defined in the figure legend.
13. A white flat hexagon can be used for any unknown monosaccharide residue.
14. Pyranose form is assumed by default for all monosaccharides except Api. A few monosaccharides have absolute configurations implicitly specified in their name (D for Abe, Bac, Dha, Kdo, Mur, Par, Tyv; L for Col; DD for Kdn, Neu, Leg, 4eLeg; LL for Pse, Aci). For all other residues, absolute configuration is assumed by default: L for Ara, Fuc, Ido, Rha, Alt, Sor, Api; and D for other monosaccharides. For details, see Table 3 at the end of these notes.
15. Any deviations from the standard definitions above need to be labeled, and less common configurations need to be stated in a figure legend or by adding the letters inside the symbol (e.g., adding D or L to the symbol). Epimers at C8 of nonulosonates can be indicated by adding "8D" or "8L" inside the symbol. Furanose rings can be indicated by adding an italicized "f" inside the symbol, and alditols can be indicated with an italicized "o" inside the symbol.
16. The two most common heptoses found in bacterial lipopolysaccharides are shown: that is, L-glycero-D-manno-heptose (LDmanHep, L-gro-D-manHep) and D-glycero-D-manno-heptose (DDmanHep, D-gro-D-manHep). Other heptoses can be shown using a white flat hexagon with a letter inside defined in the figure legend.
17. Symbols for the core sialic acids Neu5Ac, Neu5Gc, and Kdn are unchanged from the Second Edition and are meant to represent the exact structures, with modifications to be indicated in diagrams (e.g., 9Ac for 9-O-acetylation).
18. Linkages can be shown as in Figure 1.5 of the Third Edition of Essentials. There is now also the option of using the Oxford System of depicting linkages that embeds both the specificity and anomericity of the monosaccharide linkages. Dual linkages (e.g., an outgoing linkage from an aldose in open form) can be shown by double lines. Linkages involving carbon-carbon bond (e.g., in C-glycosides) can be shown in different color.
19. All monosaccharide glycosidic linkages are assumed to originate from C-1—except for 2-ketoses, which are assumed to be linked from C-2.
20. Anomeric notation and destination linkage can be indicated in IUPAC style, with or without a dash and with or without the originating carbon number (but with no commas or spacing) (e.g., Neu5Acα2-3Galβ1-4GlcNAc, Neu5Acα3Galβ4GlcNAc, or equivalents in symbol drawings).
21. An internal phosphodiester can be shown with -P- between the symbols for the linked monosaccharides, with linkage positions if preferred.
22. Abbreviations for modifications (e.g., sulfate or O-acetyl esters) will continue to follow the style of the Figure 1.5 of the Third Edition of Essentials, using attached letters, with numbers indicating linkage positions, if known (e.g., 9Ac for 9-O-acetyl group; 3S for 3-O-sulfate group; 6P for a 6-O-phosphate group; 8Me for 8-O-methyl group; 9Acy for 9-O-acyl group; 9Lt for 9-O-lactyl group; or 4,6Py for 4,6-pyruvyl group, etc.; abbreviations for multiple modifications can be concatenated).
23. For N-substituted groups it is assumed that there is only one amino group on the monosaccharide, with an already known common position (e.g., NS for N-sulfate group on glucosamine is assumed to be at the 2-position). For amino sugars in which the nitrogen is not at the most common carbon, add a number to the N (e.g., Rha4N is shown as a green triangle with 4N attached).
24. Any black shape can be used to depict unsupported residues other than monosaccharides and should be defined in the figure legend.
25. Symbol sets are available as downloadable files, including high-quality SVG objects and a presentation/slide format file the latter retaining the embedded links to PubChem.
26. A few examples of glycan structures drawn with this system are shown in the example section.
27. All downloadable symbols are in the CMYK color assignments as shown in Table 2, which were generated in Adobe Illustrator. Recommended CMYK to RGB conversion is also provided. To reproduce precise CMYK colors, click on the paint pot icon and select "more colors." Then, click on sliders in the menu and fill in numbers. Or one can copy an existing fill color by using the Eyedropper/Paintbrush and touching the color one wants.
28. A listing of abbreviated, full, and complete names of all assigned monosaccharides is shown in Table 3, in alphabetical order.

Table 2. CMYK and RGB color assignments

Color	CMYK settings	RGB settings
White	0/0/0/0	255/255/255
Blue	100/50/0/0	0/144/188
Green	100/0/100/0	0/166/81
Yellow	0/15/100/0	255/212/0
Light blue	41/5/3/0	143/204/233
Pink	0/47/24/0	246/158/161
Purple	38/88/0/0	165/67/153
Brown	32/48/76/13	161/122/77
Orange	0/65/100/0	244/121/32
Red	0/100/100/0	237/28/36

Note: CMYK colors are presented as %

Table 3. Monosaccharide abbreviations and names

Abbreviation	Short Name	Systematic name
4eLeg	4-Epilegionaminic acid	5,7-Diamino-3,5,7,9-tetradeoxy-D-glycero-D-talo-non-2-ulopyranosonic acid
6dAlt	6-Deoxy-L-altrose	6-Deoxy-L-altropyranose
6dAltNAc	N-Acetyl-6-deoxy-L-altrosamine	2-Acetamido-2,6-dideoxy-L-altropyranose
6dGul	6-Deoxy-D-gulose	6-Deoxy-D-gulopyranose
6dTal	6-Deoxy-D-talose	6-Deoxy-D-talopyranose
6dTalNAc	N-Acetyl-6-deoxy-D-talosamine	2-Acetamido-2,6-dideoxy-D-talopyranose
Abe	Abequose	3,6-Dideoxy-D-xylo-hexopyranose
Aci	Acinetaminic acid	5,7-Diamino-3,5,7,9-tetradeoxy-L-glycero-L-altro-non-2-ulopyranosonic acid
All	D-Allose	D-Allopyranose
AllA	D-Alluronic acid	D-Allopyranuronic acid
AllN	D-Allosamine	2-Amino-2-deoxy-D-allopyranose
AllNAc	N-Acetyl-D-allosamine	2-Acetamido-2-deoxy-D-allopyranose
Alt	L-Altrose	L-Altropyranose
AltA	L-Altruronic acid	L-Altropyranuronic acid
AltN	L-Altrosamine	2-Amino-2-deoxy-L-altropyranose
AltNAc	N-Acetyl-L-altrosamine	2-Acetamido-2-deoxy-L-altropyranose
Api	L-Apiose	3-C-(Hydroxymethyl)-L-erythro-tetrofuranose
Ara	L-Arabinose	L-Arabinopyranose
Bac	Bacillosamine	2,4-Diamino-2,4,6-trideoxy-D-glucopyranose
Col	Colitose	3,6-Dideoxy-L-xylo-hexopyranose
DDmanHep	D-glycero-D-manno-Heptose	D-glycero-D-manno-Heptopyranose
Dha	3-Deoxy-D-lyxo-heptulosaric acid	3-Deoxy-D-lyxo-hept-2-ulopyranosaric acid
Dig	D-Digitoxose	2,6-Dideoxy-D-ribo-hexopyranose
Fru	D-Fructose	D-arabino-Hex-2-ulopyranose
Fuc	L-Fucose	6-Deoxy-L-galactopyranose
FucNAc	N-Acetyl-L-fucosamine	2-Acetamido-2,6-dideoxy-L-galactopyranose
Gal	D-Galactose	D-Galactopyranose
GalA	D-Galacturonic acid	D-Galactopyranuronic acid
GalN	D-Galactosamine	2-Amino-2-deoxy-D-galactopyranose
GalNAc	N-Acetyl-D-galactosamine	2-Acetamido-2-deoxy-D-galactopyranose
Glc	D-Glucose	D-Glucopyranose
GlcA	D-Glucuronic acid	D-Glucopyranuronic acid
GlcN	D-Glucosamine	2-Amino-2-deoxy-D-glucopyranose
GlcNAc	N-Acetyl-D-glucosamine	2-Acetamido-2-deoxy-D-glucopyranose
Gul	D-Gulose	D-Gulopyranose
GulA	D-Guluronic acid	D-Gulopyranuronic acid
GulN	D-Gulosamine	2-Amino-2-deoxy-D-gulopyranose
GulNAc	N-Acetyl-D-gulosamine	2-Acetamido-2-deoxy-D-gulopyranose
Ido	L-Idose	L-Idopyranose
IdoA	L-Iduronic acid	L-Idopyranuronic acid
IdoN	L-Idosamine	2-Amino-2-deoxy-L-idopyranose
IdoNAc	N-Acetyl-L-idosamine	2-Acetamido-2-deoxy-L-idopyranose
Kdn	3-Deoxy-D-glycero-D-galacto-nonulosonic acid	3-Deoxy-D-glycero-D-galacto-non-2-ulopyranosonic acid
Kdo	3-Deoxy-D-manno-octulosonic acid	3-Deoxy-D-manno-oct-2-ulopyranosonic acid
Leg	Legionaminic acid	5,7-Diamino-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulopyranosonic acid
LDmanHep	L-glycero-D-manno-Heptose	L-glycero-D-manno-Heptopyranose
Lyx	D-Lyxose	D-Lyxopyranose
Man	D-Mannose	D-Mannopyranose
ManA	D-Mannuronic acid	D-Mannopyranuronic acid
ManN	D-Mannosamine	2-Amino-2-deoxy-D-mannopyranose
ManNAc	N-Acetyl-D-mannosamine	2-Acetamido-2-deoxy-D-mannopyranose
Mur	Muramic acid	2-Amino-3-O-[(R)-1-carboxyethyl]-2-deoxy-D-glucopyranose
MurNAc	N-Acetylmuramic acid	2-Acetamido-3-O-[(R)-1-carboxyethyl]-2-deoxy-D-glucopyranose
MurNGc	N-Glycolylmuramic acid	3-O-[(R)-1-Carboxyethyl]-2-deoxy-2-glycolamido-D-glucopyranose
Neu	Neuraminic acid	5-Amino-3,5-dideoxy-D-glycero-D-galacto-non-2-ulopyranosonic acid
Neu5Ac	N-Acetylneuraminic acid	5-Acetamido-3,5-dideoxy-D-glycero-D-galacto-non-2-ulopyranosonic acid
Neu5Gc	N-Glycolylneuraminic acid	3,5-Dideoxy-5-glycolamido-D-glycero-D-galacto-non-2-ulopyranosonic acid
Oli	Olivose	2,6-Dideoxy-D-arabino-hexopyranose
Par	Paratose	3,6-Dideoxy-D-ribo-hexopyranose
Pse	Pseudaminic acid	5,7-Diamino-3,5,7,9-tetradeoxy-L-glycero-L-manno-non-2-ulopyranosonic acid
Psi	D-Psicose	D-ribo-Hex-2-ulopyranose
Qui	D-Quinovose	6-Deoxy-D-glucopyranose
QuiNAc	N-Acetyl-D-quinovosamine	2-Acetamido-2,6-dideoxy-D-glucopyranose
Rha	L-Rhamnose	6-Deoxy-L-mannopyranose
RhaNAc	N-Acetyl-L-rhamnosamine	2-Acetamido-2,6-dideoxy-L-mannopyranose
Rib	D-Ribose	D-Ribopyranose
Sia	Sialic acid	Sialic acid residue of unspecified type
Sor	L-Sorbose	L-xylo-Hex-2-ulopyranose
Tag	D-Tagatose	D-lyxo-Hex-2-ulopyranose
Tal	D-Talose	D-Talopyranose
TalA	D-Taluronic acid	D-Talopyranuronic acid
TalN	D-Talosamine	2-Amino-2-deoxy-D-talopyranose
TalNAc	N-Acetyl-D-talosamine	2-Acetamido-2-deoxy-D-talopyranose
Tyv	Tyvelose	3,6-Dideoxy-D-arabino-hexopyranose
Xyl	D-Xylose	D-Xylopyranose

Clicking on the abbreviation leads to the corresponding entry in PubChem

Examples of Glycan Symbol Nomenclature

Examples of symbols and conventions for drawing glycan structures. The monosaccharide symbol set from the second edition of Essentials of Glycobiology remains intact, but has been extended to cover a wider range of monosaccharides found in nature. For reader convenience, a full table of symbols can be found in Table 1. A few examples of symbols and the use of this system to depict naturally occurring glycans are shown below: (Left panel) Branched "biantennary" N-glycan from a vertebrate, with two types of outer termini, depicted at different levels of structural details. (Right Panel) Examples of glycosaminoglycan (GAG) chains from metazoan animals, a plant glycan, and a bacterial lipopolysaccharide. [Ref: Essentials of Glycobiology [Internet]. 3rd edition, Figure 1.5]

Updates

June 5, 2017

1. SNFG Discussion Group Listing added.
2. White diamond now indicates any deoxynonulosonic acid.
3. Flattened diamond introduced for any dideoxynonulosonic acid.
4. Additional symbols added for 6dGul, 6dAltNAc, 6dTalNAc, Pse, Leg, Aci and 4eLeg.
5. Drawglycan-SNFG and Glycanbuilder 2-SNFG adopted, link to web site provided.
6. Updates to Appendix 52A. Organizations and publications adopting SNFG.
7. RGB color code provided in addition to CMYK
8. Multiple minor corrections and additions to nomenclature and rules of display.

August 31, 2016

1. Link to new Appendix 52A. Organizations and Publications Adopting SNFG.
2. Red diamond introduced for Sia (sialic acid, type unspecified). White diamond indicates any nonulosonic acid.
3. A 3D Symbol Nomenclature for Glycans (3D-SNFG) adopted, link to web site provided.
4. Multiple minor corrections and additions to nomenclature and rules of display.

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NCBI Glycans page