9.B.231.  The Die2/ALG10 Glycosyl Transferase (Die2/ALG10) Family 

The biosynthesis of the lipid-linked oligosaccharide substrate for N-linked protein glycosylation follows a highly conserved pathway at the membrane of the endoplasmic reticulum in eukaryotes. Based on the synthetic growth defect in combination with a reduced oligosaccharyltransferase activity (wbp1), Burda and Aebi 1998 identified alg10 mutant strains which accumulate lipid-linked Glc2Man9GlcNAc2. They cloned the corresponding wild-type gene and showed that Alg10p is a dolichyl-phosphoglucose-dependent glucosyltransferase which adds the terminal alpha-1,2 glucose to the lipid-linked Glc2Man9GlcNAc2 oligosaccharide. Hypoglycosylation of secreted proteins in alg10 deletion strains demonstrated that the terminal alpha-1,2-linked glucose residue is a key element in substrate recognition by the oligosaccharyltransferase. This ensures that completely assembled oligosaccharide is transferred to protein (Burda and Aebi 1998).


 

References:

Burda, P. and M. Aebi. (1998). The ALG10 locus of Saccharomyces cerevisiae encodes the α-1,2 glucosyltransferase of the endoplasmic reticulum: the terminal glucose of the lipid-linked oligosaccharide is required for efficient N-linked glycosylation. Glycobiology 8: 455-462.

Farid, A., M. Pabst, J. Schoberer, F. Altmann, J. Glössl, and R. Strasser. (2011). Arabidopsis thaliana alpha1,2-glucosyltransferase (ALG10) is required for efficient N-glycosylation and leaf growth. Plant J. 68: 314-325.

Examples:

TC#NameOrganismal TypeExample
9.B.231.1.1Dol-P-Glc:Glc(2)Man(9)GlcNAc(2)-PP-Dol alpha-1,2-glucosyltransferase (EC 2.4.1.256) (Alpha-1,2-glucosyltransferase ALG10-A) (Alpha-2-glucosyltransferase ALG10) (Asparagine-linked glycosylation protein 10) (Dolichyl-phosphoglucose-dependent glucosyltransferase ALG10)FungiDIE2 of Saccharomyces cerevisiae
 
9.B.231.1.2

α-1,2-glucosyl transferase of 458 aas and 11 TMSs. Possibly adolichyl-phosphate-glucose/glycolipid α-glucosyltransferase.

 

Glucosyl transferase of Galdieria sulphuraria (Red alga)

 
9.B.231.1.3

Alg10 of 644 aas and 11 TMSs

Alg10 of Marssonina brunnea (Marssonina leaf spot fungus)

 
9.B.231.1.4

Uncharacterized protein of 415 aas and 12 TMSs.

UP of Teredinibacter turnerae

 
9.B.231.1.5

ALG10, the α1,2-glucosyltransferase that transfers the terminal glucose residue to the lipid-linked precursor, of 509 aas and 12 TMSs.  Expressed in leaf epidermal cells with a reticular distribution pattern resembling endoplasmic reticulum (ER) localization.  An insertion mutant (alg10-1) accumulated mainly lipid-linked Glc(2) Man(9) GlcNAc(2) and displayed a severe protein underglycosylation defect. alg10-1 mutant plants had altered leaf size when grown in soil and showed activation of the unfolded protein response, increased salt sensitivity and suppression of the phenotype of α-glucosidase I-deficient plants (Farid et al. 2011).

ALG10 of Arabidopsis thaliana (Mouse-ear cress)

 
9.B.231.1.6

Dolichyl-phosphate-glucose:glycolipid α-glucosyltransferase (Die2/Alg10 family member) of 919 aas and 10 - 12 TMSs.

 

Die2 of Toxoplasma gondii