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Identify Potentially Involved Enzymes

get_involved_enzymes.Rd

This function returns all possible isoenzymes associated with the biosynthetic steps of the input glycan. Note that this function ignores the residues in glycans that cannot be matched to any enzyme rules.

Usage

get_involved_enzymes(glycans, return_list = NULL)

Arguments

glycans

A glyrepr::glycan_structure(), or a character vector of glycan structure strings supported by glyparse::auto_parse().

return_list

If NULL (default), return a list of character vectors when glycans has length greater than 1, and a single character vector when glycans has length 1. Set to TRUE to always return a list. This can be useful when you are working programmatically with unknown input length. Note that when return_list = FALSE and length(glycans) > 1, an error will be thrown.

Value

A character vector or a list of character vectors (see return_list parameter), each containing the names of enzymes involved in the biosynthesis of the corresponding glycan.

Important notes

Here are some important notes for all functions in the glyenzy package.

Applicability

All algorithms and enzyme information in glyenzy are applicable only to humans, and specifically to N-glycans and O-GalNAc glycans. Results may be inaccurate for other types of glycans (e.g., GAGs, glycolipids) or for glycans in other species (e.g., plants, insects).

Inclusiveness

The algorithm takes an intentionally inclusive approach, assuming that all possible isoenzymes capable of catalyzing a given reaction may be involved. Therefore, results should be interpreted with caution.

For example, in humans, detection of the motif "Neu5Ac(a2-3)Gal(b1-" will return both "ST3GAL3" and "ST3GAL4". In reality, only one of them might be active, depending on factors such as tissue specificity.

Only "concrete" glycans

The function only works for glycans containing concrete residues (e.g., "Glc", "GalNAc"), and not for glycans with generic residues (e.g., "Hex", "HexNAc").

Substituents

Subtituents (e.g. sulfation, phosphorylation) is not supported yet, and the algorithms might fail for glycans with subtituents. If your glycans contains substituents, use glyrepr::remove_substituents() to get clean glycans.

Incomplete glycan structures

If the glycan structure is incomplete or partially degraded, the result may be misleading.

Starting points

  • For N-glycans, the starting structure is assumed to be "Glc(3)Man(9)GlcNAc(2)", the N-glycan precursor transfered to Asn by OST.

  • For O-GalNAc glycans, the starting structure is assumed to be "GalNAc(a1-".

  • For O-GlcNAc glycans, the starting structure is assumed to be "GlcNAc(b1-".

  • For O-Man glycans, the starting structure is assumed to be "Man(a1-".

  • For O-Fuc glycans, the starting structure is assumed to be "Fuc(a1-".

  • For O-Glc glycans, the starting structure is assumed to be "Glc(b1-".

Examples

library(glyrepr)
library(glyparse)

# Use `glycan_structure()`
glycans <- auto_parse(c(
  "GlcNAc(b1-2)Man(a1-3)[Man(a1-6)]Man(b1-4)GlcNAc(b1-4)GlcNAc(b1-",
  "GlcNAc(b1-2)Man(a1-3)[GlcNAc(b1-2)Man(a1-6)]Man(b1-4)GlcNAc(b1-4)GlcNAc(b1-"
))
get_involved_enzymes(glycans)
#> [[1]]
#> [1] "MOGS"   "GANAB"  "MAN1B1" "MAN1A1" "MAN1A2" "MAN1C1" "MAN2A1" "MAN2A2"
#> [9] "MGAT1" 
#> 
#> [[2]]
#>  [1] "MOGS"   "GANAB"  "MAN1B1" "MAN1A1" "MAN1A2" "MAN1C1" "MAN2A1" "MAN2A2"
#>  [9] "MGAT1"  "MGAT2" 
#> 

# Or use characters directly
get_involved_enzymes("GlcNAc(b1-2)Man(a1-3)[Man(a1-6)]Man(b1-4)GlcNAc(b1-4)GlcNAc(b1-")
#> [1] "MOGS"   "GANAB"  "MAN1B1" "MAN1A1" "MAN1A2" "MAN1C1" "MAN2A1" "MAN2A2"
#> [9] "MGAT1"