Glycan Structures

KEGG GLYCAN is a collection of experimentally determined glycan structures, containing all unique structures taken from CarbBank, structures entered from recent publications, and structures present in KEGG pathways. Each structure is identified by the G number, such as G00242 for sialyl Lewis x, and displayed with predefined monosaccharide codes shown below. The structure may also be converted to the SNFG (Symbol Nomenclature for Glycans) representation by clicking on the SNFG button.

Glycans in Pathways and Diseases

KEGG GLYCAN is tightly integrated with other KEGG resources, especially KEGG PATHWAY, KEGG MODULE, KEGG NETWORK and KEGG DISEASE. In the KEGG PATHWAY database the section on: contains metabolic pathway maps for glycans. Some of them contain an additional representation of glycan biosynthesis or degradation, called the glycan structure map. For example, N-glycan biosynthesis is shown both as a pathway map and a structure map in map00510.

The human pathway map hsa00510 for N-glycan biosynthesis is now linked to the network variation map nt06015 in the KEGG NETWORK database, which contains disease-related gene variants; in this case, germline mutations for congenital disorder of glycosylation.

It is interesting to note that the correlation is often observed between KEGG modules defined as conserved functional units across species and KEGG network units defined from disease-related gene variants in Homo sapiens. Here are some examples (see also KEGG COMPOUND).


Pathway Module Disease Network Content

hsa00510       N-glycan biosynthesis
hsa00510+M00055 hsa_M00055     N-glycan precursor biosynthesis
hsa00510+H00118   H00118   Congenital disorder of glycosylation
      nt06015 N-Glycan precursor biosynthesis

hsa00515       Mannose type O-glycan biosynthesis
hsa00515+M00872 hsa_M00872     O-glycan biosynthesis, mannose type (core M3)
hsa00515+H02307   H02307   Muscular dystrophy-dystroglycanopathy
      nt06013 O-Glycan precursor biosynthesis

hsa00531       Glycosaminoglycan degradation
hsa00531+M00076
  +M00078+M00079
hsa_M00076
hsa_M00078
hsa_M00079
    Dermatan sulfate degradation
Heparan sulfate degradation
Keratan sulfate degradation
hsa00531+H00421   H00421   Mucopolysaccharidosis
      nt06012 Glycosaminoglycan degradation


The roles of glycans in various cellular processes may be examined with other pathway maps in the KEGG PATHWAY database, such as: The roles of glycans in cancers are represented in a KEGG pathway map for: and a BRITE table file for:

Glycosyltransferases

The KEGG Orthology (KO) system is a method to characterize gene/protein functions across organisms. Experimental evidence in specific organisms is extended to other organisms by defining KO groups (or K number entries) in the KEGG ortholog annotation procedure. The K number entries for glycosyltransferases are finely classified ortholog groups distinguishing known substrate specificity.

Glycan Binding Proteins

Different types of glycan binding proteins are organized as K number entries and classified as a functional hierarchy of KEGG BRITE.

KCaM Search Tool

KCaM is a database search program for similar glycan structures. It can be used to search against KEGG GLYCAN or CarbBank. A query glycan structure may be entered with the KegDraw tool.

References
  1. Hashimoto, K., Goto, S., Kawano, S., Aoki-Kinoshita, K.F., Ueda, N., Hamajima, M., Kawasaki, T., and Kanehisa, M.; KEGG as a glycome informatics resource. Glycobiology 16, 63R-70R (2006). [pubmed] [pdf]
  2. Kanehisa, M.; KEGG GLYCAN. In "A Practical Guide to Using Glycomics Databases" (Aoki-Kinoshita, K.F., ed.), pp. 177-193, Springer (2017).
  3. Hashimoto, K., Kawano, S., Goto, S., Aoki-Kinoshita, K., Kawashima, M., and Kanehisa, M.; A global representation of the carbohydrate structures: a tool for the analysis of glycan. Genome Informatics 16(1), 214-222 (2005). [pubmed]
  4. Hashimoto, K., Tokimatsu, T., Kawano, S., Yoshizawa, A.C., Okuda, S., Goto, S., and Kanehisa, M.; Comprehensive analysis of glycosyltransferases in eukaryotic genomes for structural and functional characterization of glycans. Carbohydr. Res. 344, 881-887 (2009). [pubmed]
  5. Aoki, K.F., Yamaguchi, A., Ueda, N., Akutsu, T., Mamitsuka, H., Goto, S., and Kanehisa, M.; KCaM (KEGG Carbohydrate Matcher): a software tool for analyzing the structures of carbohydrate sugar chains. Nucleic Acids Res. 32, W267-W272 (2004). [pubmed] [pdf]

Last updated: May 21, 2021