PubChem | Glycans | Symbol Nomenclature for Glycans (SNFG)

History of the SNFG

Issues regarding nomenclature are more controversial than scientific ones, as there is never one correct answer, and some aspects are matters of opinion and taste. In 1978, Kornfeld presented a system for symbolic representation of vertebrate glycans, which enjoyed popular use and was eventually adopted and standardized for the first edition of the Essentials of Glycobiology textbook (1999). While this adoption increased usage, the system had limitations and did not use color. Anticipating a second edition, the editors updated the nomenclature and made it available to the community in 2004 before publication. This was widely adopted and disseminated, especially by the NIGMS-funded Consortium for Functional Glycomics (thus sometimes being referred to as the "CFG Nomenclature"). After final publication of the Second Edition in 2009, acceptance by the community remained incomplete, and individual variations began to appear. Anticipating a third edition, a reorganized group of Essentials editors (supported by the NHLBI-funded Programs of Excellence in Glycoscience) further refined and updated the symbol nomenclature, this time reaching beyond vertebrate glycans and considering input from others using related systems. The editors also coordinated with the IUPAC Carbohydrate Nomenclature committee, linked each monosaccharide symbol to the corresponding entry in PubChem at NCBI/NLM, and initiated coordination with other long-term online resources. The system became an online advance Appendix to the Third Edition of Essentials. New symbols were added, but to ensure compatibility with prior publications, no changes were made to symbols in the Second Edition. For this historical reason, chemical features and configurations associated with shapes and colors are internally consistent only for some monosaccharides. For example, many of the nonulosonates do not conform to the stereochemical features otherwise represented in specified columns. Symbol colors are specified in CMYK and RGB settings. Linkages can be shown as in the Second Edition system using IUPAC style, with the originating carbon assumed, and hyphens (not commas) used as an option. The Oxford system of angled monosaccharide linkages with embedded specificity and anomericity can also be used.

Realizing the need for a standard acronym, the Essentials editors suggested SNFG: Symbol Nomenclature For Glycans. This generic name recognizes the fact that while the update arose from the editors need to standardize a previous system for the textbook, many others eventually contributed towards its final creation. The system thus belongs to the community. Accordingly, a broadly representative SNFG Discussion Group now works with the NCBI on periodic updates. The system is widely accepted in the literature and adopted by many major journals. The efforts of the SNFG represent another step towards mainstreaming glycan bioinformatics. This is a critical step to complete the description of the molecular and cellular features of all living systems.

Following the initial release in 2015, the SNFG discussion group has worked with the NCBI and PubChem to generate the Updates as shown here.