N型糖鎖合成経路（３）

Dol-P-Man:Man(7)GlcNAc(2)-PP-Dol alpha-1,6-mannosyltransferase

EC=2.4.1.260
Alternative name(s):
Asparagine-linked glycosylation protein 12 homolog
Short name=hALG12
Dolichyl-P-Man:Man(7)GlcNAc(2)-PP-dolichyl-alpha-1,6-mannosyltransferase
Mannosyltransferase ALG12 homolog
Membrane protein SB87

Function

Adds the eighth mannose residue in an alpha-1,6 linkage onto the dolichol-PP-oligosaccharide precursor (dolichol-PP-Man7GlcNAc2) required for protein glycosylation.
Catalytic activity
Dolichyl beta-D-mannosyl phosphate + D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-D-Man-alpha-(1->6))-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol = D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->6))-D-Man-alpha-(1->6))-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.
Pathway
Protein modification; protein glycosylation.
Subcellular location
Endoplasmic reticulum membrane; Multi-pass membrane protein Probable.
Tissue specificity
Expressed in fibroblasts.
Involvement in disease
Congenital disorder of glycosylation 1G (CDG1G) [MIM:607143]: A multisystem disorder caused by a defect in glycoprotein biosynthesis and characterized by under-glycosylated serum glycoproteins. Congenital disorders of glycosylation result in a wide variety of clinical features, such as defects in the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. The broad spectrum of features reflects the critical role of N-glycoproteins during embryonic development, differentiation, and maintenance of cell functions.
Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.1 Ref.8 Ref.9 Ref.10 Ref.11
Sequence similarities
Belongs to the glycosyltransferase 22 family.

Dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase

EC=2.4.1.267
Alternative name(s):
Asparagine-linked glycosylation protein 6 homolog
Dol-P-Glc:Man(9)GlcNAc(2)-PP-Dol alpha-1,3-glucosyltransferase
Dolichyl-P-Glc:Man9GlcNAc2-PP-dolichyl glucosyltransferase

Function

Adds the first glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation. Transfers glucose from dolichyl phosphate glucose (Dol-P-Glc) onto the lipid-linked oligosaccharide Man9GlcNAc(2)-PP-Dol.
Catalytic activity
Dolichyl beta-D-glucosyl phosphate + D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol = D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.
Pathway
Protein modification; protein glycosylation.
Subcellular location
Endoplasmic reticulum membrane; Multi-pass membrane protein Potential.
Involvement in disease
Congenital disorder of glycosylation 1C (CDG1C) [MIM:603147]: A multisystem disorder caused by a defect in glycoprotein biosynthesis and characterized by under-glycosylated serum glycoproteins. Congenital disorders of glycosylation result in a wide variety of clinical features, such as defects in the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. The broad spectrum of features reflects the critical role of N-glycoproteins during embryonic development, differentiation, and maintenance of cell functions.
Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.1 Ref.7 Ref.8 Ref.9 Ref.11 Ref.12 Ref.14
Sequence similarities
Belongs to the ALG6/ALG8 glucosyltransferase family.

Probable dolichyl pyrophosphate Glc1Man9GlcNAc2 alpha-1,3-glucosyltransferase

EC=2.4.1.265
Alternative name(s):
Asparagine-linked glycosylation protein 8 homolog
Dol-P-Glc:Glc(1)Man(9)GlcNAc(2)-PP-dolichyl alpha-1,3-glucosyltransferase
Dolichyl-P-Glc:Glc1Man9GlcNAc2-PP-dolichyl glucosyltransferase

Function

Adds the second glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation. Transfers glucose from dolichyl phosphate glucose (Dol-P-Glc) onto the lipid-linked oligosaccharide Glc1Man9GlcNAc(2)-PP-Dol By similarity.
Catalytic activity
Dolichyl beta-D-glucosyl phosphate + D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol = D-Glc-alpha-(1->3)-D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.
Pathway
Protein modification; protein glycosylation.
Subcellular location
Endoplasmic reticulum membrane; Multi-pass membrane protein By similarity.
Involvement in disease
Congenital disorder of glycosylation 1H (CDG1H) [MIM:608104]: A multisystem disorder caused by a defect in glycoprotein biosynthesis and characterized by under-glycosylated serum glycoproteins. Congenital disorders of glycosylation result in a wide variety of clinical features, such as defects in the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. The broad spectrum of features reflects the critical role of N-glycoproteins during embryonic development, differentiation, and maintenance of cell functions.
Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.6
Sequence similarities
Belongs to the ALG6/ALG8 glucosyltransferase family.

Dol-P-Glc:Glc(2)Man(9)GlcNAc(2)-PP-Dol alpha-1,2-glucosyltransferase

EC=2.4.1.256
Alternative name(s):
Alpha-1,2-glucosyltransferase ALG10-A
Alpha-2-glucosyltransferase ALG10-A
Asparagine-linked glycosylation protein 10 homolog A

Function

Adds the third glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation. Transfers glucose from dolichyl phosphate glucose (Dol-P-Glc) onto the lipid-linked oligosaccharide Glc2Man9GlcNAc(2)-PP-Dol.
Catalytic activity
Dolichyl beta-D-glucosyl phosphate + D-Glc-alpha-(1->3)-D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol = D-Glc-alpha-(1->2)-D-Glc-alpha-(1->3)-D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.
Pathway
Protein modification; protein glycosylation.
Subcellular location
Endoplasmic reticulum membrane; Multi-pass membrane protein.
Sequence similarities
Belongs to the ALG10 glucosyltransferase family.