N-GlycoSite

Purpose: This tool highlights and tallies predicted N-linked glycosylation sites (Nx[ST] patterns, where x can be any amino acid).

Details:
During glycosylation, an oligosaccharide chain is attached to asparagine (N) occurring in the tripeptide sequence N-X-S or N-X-T, where X can be any amino acid except Pro. This sequence is called a glycosylation sequon. The N-GlycoSite tool marks and tallies the locations where this pattern occurs.

The likelihood of N-linked glycosylation of a particular site can be influenced by the context in which it is embedded, and could be expanded to a 4-amino acid NX[ST]Z pattern, where the amino acid in the X or Z position can be important determinants of glycosylation efficiency. For example, a proline in position X or Z strongly disfavors N-linked glycosylation.

O-linked glycosylation signals are more difficult predict, but one can estimate their positions using the NetPhos program at Center for Biological Sequence Analysis.

Input:
Input can be one amino acid sequence, or an alignment of amino acid sequences. If you just want to tally the number of N-glycosylation sites, the protein sequences do not need to be aligned.

Option:
A second position proline (site pattern NP[ST]) is strongly disfavored for glycosylation. Thus the default option excludes these patterns. You may uncheck the box to include them.

References:

1. Zhang M et al., Glycobiology. 14(12):1229-46 (2004) -- please cite this reference if you use our tool in a publication.
2. Marshall RD, Biochem Soc Symp. 40:17-26 (1974)
3. Kasturi et al., Biochem J. 323 (Pt 2):415-9 (1997)
4. Mellquist JL et al., Biochemistry. 37(19):6833-7 (1998)