N-glycan LLO assembly I — cytoplasmic face (to Man5GlcNAc2-PP-dolichol); DPAGT1/ALG13/ALG14/ALG1/ALG2/ALG11

N-linked glycosylation begins with the stepwise assembly of the dolichol-linked oligosaccharide (LLO, or dolichol-PP-oligosaccharide) on the cytoplasmic face of the endoplasmic-reticulum membrane. Using nucleotide-sugar donors from the cytosol, the pathway builds a Man5GlcNAc2 glycan on the polyprenol carrier dolichyl phosphate before the intermediate is flipped into the ER lumen. DPAGT1 (GlcNAc-1-phosphotransferase, the first and committed step, and the tunicamycin target) transfers GlcNAc-1-P from UDP-GlcNAc onto dolichyl phosphate to give GlcNAc-PP-dolichol; the bipartite UDP-GlcNAc transferase ALG13/ALG14 (ALG13 catalytic, ALG14 membrane-anchoring) adds the second GlcNAc to form the chitobiose core GlcNAc2-PP-dolichol; ALG1 (beta-1,4-mannosyltransferase) adds the first mannose; the bifunctional ALG2 (alpha-1,3 and alpha-1,6 mannosyltransferase) adds the second and third mannoses to give Man3GlcNAc2-PP-dolichol; and ALG11 (alpha-1,2-mannosyltransferase) adds the fourth and fifth mannoses to complete Man5GlcNAc2-PP-dolichol, the final cytoplasmic-face intermediate (subsequently flipped to the lumen by the RFT1 flippase, and extended by the lumenal ALG enzymes). All the mannose-addition steps in this segment use GDP-mannose. Inherited defects in each step cause a congenital disorder of glycosylation (CDG type I): DPAGT1-CDG (and a congenital myasthenic syndrome), ALG13-CDG (an X-linked developmental/epileptic encephalopathy), ALG14-CDG (congenital myasthenic syndrome), ALG1-CDG, ALG2-CDG (and CMS14) and ALG11-CDG.

MODULE:n_glycan_llo_assembly_cytoplasmicDRAFTMetabolic Pathwaymodules/n_glycan_llo_assembly_cytoplasmic.yaml
dolichol-linked oligosaccharide biosynthetic processGO:0006488 protein N-linked glycosylationGO:0006487
GO:0006488
dolichol-linked oligosaccharide biosynthetic process
The module is grounded in dolichol-linked oligosaccharide biosynthetic process (GO:0006488); it covers the cytoplasmic-face assembly of Man5GlcNAc2-PP-dolichol.
GO:0006487
protein N-linked glycosylation
The completed LLO is the donor for protein N-linked glycosylation (GO:0006487); each enzyme's loss reduces N-glycan occupancy (CDG type I).
Reactome:R-HSA-446193
Biosynthesis of the N-glycan precursor (dolichol lipid-linked oligosaccharide, LLO) and transfer to a nascent protein
Step order, intermediates and reaction stoichiometries follow the human Reactome LLO biosynthesis sub-pathway (R-HSA-446191/446207/446218/446208 for the cytoplasmic-face steps).
file:human/DPAGT1/DPAGT1-ai-review.yaml
DPAGT1 gene review (human)
The committed GlcNAc-1-P transfer to Dol-P (UniProtKB:Q9H3H5, GO:0003975) matches the completed human DPAGT1 review.
file:human/ALG13/ALG13-ai-review.yaml
ALG13 gene review (human)
The catalytic subunit of the second-GlcNAc transfer (UniProtKB:Q9NP73, GO:0004577) matches the completed human ALG13 review.
file:human/ALG14/ALG14-ai-review.yaml
ALG14 gene review (human)
The ER-membrane anchor of the ALG13/ALG14 transferase (UniProtKB:Q96F25, GO:0043495) matches the completed human ALG14 review.
file:human/ALG1/ALG1-ai-review.yaml
ALG1 gene review (human)
The first-mannose beta-1,4-mannosyltransferase step (UniProtKB:Q9BT22, GO:0004578) matches the completed human ALG1 review.
file:human/ALG2/ALG2-ai-review.yaml
ALG2 gene review (human)
The second/third-mannose alpha-1,3/1,6-mannosyltransferase step (UniProtKB:Q9H553, GO:0004378/GO:0102704) matches the completed human ALG2 review.
file:human/ALG11/ALG11-ai-review.yaml
ALG11 gene review (human)
The fourth/fifth-mannose alpha-1,2-mannosyltransferase step (UniProtKB:Q2TAA5, GO:0004377) matches the completed human ALG11 review.
YeastPathways:GLUCOSE-MANNOSYL-CHITO-DOLICHOL
lipid-linked oligosaccharide biosynthesis (S. cerevisiae, SGD YeastPathways)
The YeastCyc frame spans both LLO modules. Cytoplasmic-face reactions: 2.7.8.15-RXN (ALG7), 2.4.1.141-RXN (ALG13/ALG14), RXN3O-9818 (ALG1), 2.4.1.132-RXN and RXN3O-378 (ALG2), RXN3O-379 and 2.4.1.131-RXN (ALG11). All gene assignments were retained.
PMID:15615718
Two proteins homologous to the N- and C-terminal domains of the bacterial glycosyltransferase Murg are required for the second step of dolichyl-linked oligosaccharide synthesis in Saccharomyces cerevisiae.
Yeast ALG13 and ALG14 are essential MurG-like halves required for GlcNAc2-PP-Dol formation.
PMID:16100110
Alg14 recruits Alg13 to the cytoplasmic face of the endoplasmic reticulum to form a novel bipartite UDP-N-acetylglucosamine transferase required for the second step of N-linked glycosylation.
Alg14 is the membrane anchor that recruits catalytic Alg13 to the cytosolic face of the ER.
We show that Alg14 functions as a membrane anchor that recruits Alg13 to the cytosolic face of the ER, where catalysis of GlcNAc2-PP-dol occurs.
PMID:16100113
Biosynthesis of lipid-linked oligosaccharides in Saccharomyces cerevisiae: Alg13p and Alg14p form a complex required for the formation of GlcNAc(2)-PP-dolichol.
Alg13p and Alg14p form the complex that makes GlcNAc2-PP-Dol.
PMID:19282279
Biochemical characterization and membrane topology of Alg2 from Saccharomyces cerevisiae as a bifunctional alpha1,3- and 1,6-mannosyltransferase involved in lipid-linked oligosaccharide biosynthesis.
Yeast Alg2 transfers both the alpha-1,3- and alpha-1,6-linked mannoses to Man1GlcNAc2-PP-Dol.
PMID:11278778
The yeast ALG11 gene specifies addition of the terminal alpha 1,2-Man to the Man5GlcNAc2-PP-dolichol N-glycosylation intermediate formed on the cytosolic side of the endoplasmic reticulum.
ALG11 adds the alpha-1,2 mannoses that complete Man5GlcNAc2-PP-Dol on the cytosolic face.
PMID:23751184
N-linked protein glycosylation in the endoplasmic reticulum.
Review of LLO assembly on both faces of the ER membrane, centred on S. cerevisiae.
6Nodes
5Parts
0Variant Sets
0Variants
6Annotons
4Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:n_glycan_llo_assembly_cytoplasmic deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Reaction chaining (advisory)

✓ every PRECEDES step chains, or its break is acknowledged via chaining_status.

  • dpagt1_step → alg13_14_step [NOT_CHECKED]
    A dolichol-linked glycan intermediate links the steps; no CoA carrier is involved.
  • alg13_14_step → alg1_step [NOT_CHECKED]
    A dolichol-linked glycan intermediate links the steps; no CoA carrier is involved.
  • alg1_step → alg2_step [NOT_CHECKED]
    A dolichol-linked glycan intermediate links the steps; no CoA carrier is involved.
  • alg2_step → alg11_step [NOT_CHECKED]
    A dolichol-linked glycan intermediate links the steps; no CoA carrier is involved.

Function consistency and core coverage

16 gene-function check(s) reflected in core functions · 0 conflict(s) · 2 evidence or coverage gap(s) (26 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

AnnotonParticipantFunctionAssessment
dpagt1_activity DPAGT1 (human)
UniProtKB:Q9H3H5
Family Representative 		UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase activity
GO:0003975 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
dpagt1_activity ALG7 (Saccharomyces cerevisiae)
UniProtKB:P07286
Family Representative 		UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase activity
GO:0003975 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
dpagt1_activity alg7 (Schizosaccharomyces pombe)
UniProtKB:P42881
Family Representative 		UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase activity
GO:0003975 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg13_activity ALG13 (human)
UniProtKB:Q9NP73
Family Representative 		N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activity
GO:0004577 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg13_activity ALG13 (Saccharomyces cerevisiae)
UniProtKB:P53178
Family Representative 		N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activity
GO:0004577 		Annotation Supported
A retained annotation or curated replacement supports this function, but core_functions does not yet reflect it.
alg13_activity alg13 (Schizosaccharomyces pombe)
UniProtKB:O14190
Family Representative 		N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activity
GO:0004577 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg14_activity ALG14 (human)
UniProtKB:Q96F25
Family Representative 		protein-membrane adaptor activity
GO:0043495 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg14_activity ALG14 (Saccharomyces cerevisiae)
UniProtKB:P38242
Family Representative 		protein-membrane adaptor activity
GO:0043495 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg14_activity alg14 (Schizosaccharomyces pombe)
UniProtKB:O14199
Family Representative 		protein-membrane adaptor activity
GO:0043495 		Annotation Supported
A retained annotation or curated replacement supports this function, but core_functions does not yet reflect it.
alg1_activity ALG1 (human)
UniProtKB:Q9BT22
Family Representative 		chitobiosyldiphosphodolichol beta-mannosyltransferase activity
GO:0004578 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg1_activity ALG1 (Saccharomyces cerevisiae)
UniProtKB:P16661
Family Representative 		chitobiosyldiphosphodolichol beta-mannosyltransferase activity
GO:0004578 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg1_activity alg1 (Schizosaccharomyces pombe)
UniProtKB:O13933
Family Representative 		chitobiosyldiphosphodolichol beta-mannosyltransferase activity
GO:0004578 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg2_activity ALG2 (human)
UniProtKB:Q9H553
Family Representative 		GDP-Man:Man(1)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activity
GO:0004378 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg2_activity ALG2 (Saccharomyces cerevisiae)
UniProtKB:P43636
Family Representative 		GDP-Man:Man(1)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activity
GO:0004378 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg2_activity alg2 (Schizosaccharomyces pombe)
UniProtKB:Q96WW6
Family Representative 		GDP-Man:Man(1)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activity
GO:0004378 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg11_activity ALG11 (human)
UniProtKB:Q2TAA5
Family Representative 		GDP-Man:Man(3)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activity
GO:0004377 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg11_activity ALG11 (Saccharomyces cerevisiae)
UniProtKB:P53954
Family Representative 		GDP-Man:Man(3)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activity
GO:0004377 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
alg11_activity alg11 (Schizosaccharomyces pombe)
UniProtKB:O74878
Family Representative 		GDP-Man:Man(3)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activity
GO:0004377 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
dpagt1_activity GlcNAc-1-phosphotransferase family (DPAGT1)
PANTHER:PTHR10571
Family 		UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase activity
GO:0003975 		Family Supported
Family review supports GO:0003975 FAMILY_WIDE. Asserted by n_glycan_llo_assembly_cytoplasmic; accepted by ALG7, gpt2 and DPAGT1.
alg13_activity ALG13 glycosyltransferase-28 family (catalytic subunit)
PANTHER:PTHR12867
Family 		N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activity
GO:0004577 		Family Supported
Family review supports GO:0004577 FAMILY_WIDE. Core activity of S. pombe alg13 and human ALG13 in the n_glycan_llo_assembly_cytoplasmic module.
alg13_activity ALG13 glycosyltransferase-28 family (catalytic subunit)
PANTHER:PTHR47043
Family 		N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activity
GO:0004577 		Family Supported
Family review supports GO:0004577 FAMILY_WIDE. Accepted by ALG13, as part of the ALG13/ALG14 enzyme in n_glycan_llo_assembly_cytoplasmic.
alg14_activity ALG14 family (membrane-anchoring subunit)
PANTHER:PTHR12154
Family 		protein-membrane adaptor activity
GO:0043495 		Family Supported
Family review supports GO:0043495 FAMILY_WIDE. Asserted by n_glycan_llo_assembly_cytoplasmic; accepted by ALG14, alg14 and human ALG14.
alg1_activity ALG1 beta-mannosyltransferase family
PANTHER:PTHR13036:SF0
Family 		chitobiosyldiphosphodolichol beta-mannosyltransferase activity
GO:0004578 		Family Supported
Family review supports GO:0004578 for PANTHER:PTHR13036:SF0. ALG1 (SF0, SF1); n_glycan_llo_assembly_cytoplasmic selects the base family, which also takes in ALG1L2.
alg1_activity ALG1 beta-mannosyltransferase family
PANTHER:PTHR13036:SF1
Family 		chitobiosyldiphosphodolichol beta-mannosyltransferase activity
GO:0004578 		Family Supported
Family review supports GO:0004578 for PANTHER:PTHR13036:SF1. ALG1 (SF0, SF1); n_glycan_llo_assembly_cytoplasmic selects the base family, which also takes in ALG1L2.
alg2_activity ALG2 mannosyltransferase family
PANTHER:PTHR45918
Family 		GDP-Man:Man(1)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activity
GO:0004378 		Family Supported
Family review supports GO:0004378 FAMILY_WIDE. Asserted by n_glycan_llo_assembly_cytoplasmic; accepted by every reviewed member.
alg11_activity ALG11 mannosyltransferase family
PANTHER:PTHR45919
Family 		GDP-Man:Man(3)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activity
GO:0004377 		Family Supported
Family review supports GO:0004377 FAMILY_WIDE. Asserted by n_glycan_llo_assembly_cytoplasmic; accepted by every reviewed member.

Gene-review completeness (18/18 grounded genes reviewed)

17 complete review(s) · 6 with deep research · 0 missing review · 12 reviewed but lacking deep research

Gene Review Complete Deep research
alg1 O13933 ✓ ✓ ✗
ALG1 P16661 ✓ ✓ ✓
ALG1 Q9BT22 ✓ ✓ ✗
alg11 O74878 ✓ ✓ ✗
ALG11 P53954 ✓ ✓ ✓
ALG11 Q2TAA5 ✓ ✓ ✗
alg13 O14190 ✓ ✓ ✗
ALG13 P53178 ✓ ✓ ✓
ALG13 Q9NP73 ✓ ✓ ✗
alg14 O14199 ✓ ✓ ✗
ALG14 P38242 ✓ ✓ ✓
ALG14 Q96F25 ✓ ✓ ✗
ALG2 P43636 ✓ ✓ ✓
alg2 Q96WW6 ✓ ✓ ✗
ALG2 Q9H553 ✓ ✓ ✗
ALG7 P07286 ✓ ✓ ✓
DPAGT1 Q9H3H5 ✓ 28/29 ✗
gpt2 P42881 ✓ ✓ ✗

Details

Context
eukaryotesNCBITaxon:2759
cytoplasmic side of endoplasmic reticulum membraneGO:0098554 endoplasmic reticulum membraneGO:0005789
N-glycan LLO assembly, cytoplasmic face (to Man5GlcNAc2-PP-dolichol)Metabolic Pathwayn_glycan_llo_assembly_cytoplasmic
dolichol-linked oligosaccharide biosynthetic processGO:0006488 protein N-linked glycosylationGO:0006487
Context
eukaryotesNCBITaxon:2759
cytoplasmic side of endoplasmic reticulum membraneGO:0098554 endoplasmic reticulum membraneGO:0005789

Cytoplasmic-face segment of dolichol-linked oligosaccharide (LLO) assembly, grounded to the human enzymes DPAGT1 (UniProtKB:Q9H3H5, GO:0003975, EC 2.7.8.15), the ALG13/ALG14 UDP-GlcNAc transferase (Q9NP73 GO:0004577 catalytic + Q96F25 GO:0043495 anchor, EC 2.4.1.141), ALG1 (Q9BT22, GO:0004578, EC 2.4.1.142), ALG2 (Q9H553, GO:0004378/GO:0102704, EC 2.4.1.132/257) and ALG11 (Q2TAA5, GO:0004377, EC 2.4.1.131). GO molecular-function/location terms were taken from the completed human gene reviews and verified against the local go.db; Reactome reaction ids/titles were verified against the local reactome cache. Each step uses a PANTHER family selector with the human enzyme as representative so the module generalises across orthologs/paralogs. The ALG13/ALG14 step is modelled as a PROTEIN_COMPLEX node (catalytic + membrane-anchoring subunits; ALG14's core function is the non-catalytic adaptor activity GO:0043495, not a transferase term). Sugar donors are cytosolic UDP-GlcNAc (DPAGT1, ALG13/14) and GDP-mannose (ALG1, ALG2, ALG11). Downstream, Man5GlcNAc2-PP-Dol is flipped into the ER lumen by the RFT1 flippase (already reviewed) and extended by the lumenal ALG enzymes (ALG3, ALG9, ALG12, ALG6, ALG8, ALG10 — a separate module), then transferred to protein by the oligosaccharyltransferase. Dolichol-phosphate and the Dol-P-Man/Dol-P-Glc donors are supplied by a further module (DOLK, SRD5A3, DPM1/2/3, MPDU1, ALG5). Disorders: each step's loss is a CDG type I (DPAGT1-, ALG13-, ALG14-, ALG1-, ALG2-, ALG11-CDG), several also presenting as congenital myasthenic syndromes. ALIGN (YeastPathways project, 2026-10): S. cerevisiae (ALG7 P07286, ALG13 P53178, ALG14 P38242, ALG1 P16661, ALG2 P43636, ALG11 P53954) and S. pombe (alg7 P42881, alg13 O14190, alg14 O14199, alg1 O13933, alg2 Q96WW6, alg11 O74878) exemplars were added to every role; the ALG names are yeast-derived, and the YeastCyc gene assignments in GLUCOSE-MANNOSYL-CHITO-DOLICHOL are correct. The ALG13 role now lists two PANTHER families because S. cerevisiae ALG13 is placed in PTHR47043 while human and S. pombe ALG13 are in PTHR12867. Connections were converted to PRECEDES. GO-CAM disagreements: the SGD model places every ER-membrane enzyme in cytosol, gives ALG11 only the parent GO:0000026 and types the ALG2 alpha-1,6 step with GO:0033164; the PomBase model agrees with the step order and adds causal links through the rft1 flippase to the lumenal module.

Connections

GlcNAc-PP-dolichol from DPAGT1 receives the second GlcNAc from the ALG13/ALG14 transferase.
The chitobiose core GlcNAc2-PP-dolichol is the acceptor for the first mannose (ALG1).
alg1_step -> alg2_step Precedes
Man1GlcNAc2-PP-dolichol from ALG1 is extended by ALG2 with two more mannoses.
alg2_step -> alg11_step Precedes
Man3GlcNAc2-PP-dolichol from ALG2 is extended by ALG11 to Man5GlcNAc2-PP-dolichol.
Part 1: committed step (GlcNAc-1-P onto dolichyl phosphate)
UDP-GlcNAc + dolichyl phosphate to GlcNAc-PP-dolicholReactiondpagt1_step

Annotons

DPAGT1: GlcNAc-1-phosphotransferase
dpagt1_activity
Participant: Family: GlcNAc-1-phosphotransferase family (DPAGT1)
Family:
GlcNAc-1-phosphotransferase family (DPAGT1)PANTHER:PTHR10571
Representative Members: DPAGT1 (human)UniProtKB:Q9H3H5 ALG7 (Saccharomyces cerevisiae)UniProtKB:P07286 alg7 (Schizosaccharomyces pombe)UniProtKB:P42881

Function

UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase activityGO:0003975
Substrates: UDP-GlcNAc dolichyl phosphate
Products: GlcNAc-PP-dolichol UMP

Locations

cytoplasmic side of endoplasmic reticulum membraneGO:0098554

First and committed step; deficiency = DPAGT1-CDG (CDG-Ij) and a congenital myasthenic syndrome.

Part 2: second GlcNAc (chitobiose core)
GlcNAc-PP-dolichol to GlcNAc2-PP-dolicholProtein Complexalg13_14_step

Annotons

ALG13: catalytic subunit of the UDP-GlcNAc transferase
alg13_activity
Participant: Family: ALG13 glycosyltransferase-28 family (catalytic subunit)
Family:
ALG13 glycosyltransferase-28 family (catalytic subunit)
Representative Members: ALG13 (human)UniProtKB:Q9NP73 ALG13 (Saccharomyces cerevisiae)UniProtKB:P53178 alg13 (Schizosaccharomyces pombe)UniProtKB:O14190

Function

N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase activityGO:0004577
Substrates: UDP-GlcNAc GlcNAc-PP-dolichol
Products: GlcNAc2-PP-dolichol (chitobiose core) UDP

Locations

cytoplasmic side of endoplasmic reticulum membraneGO:0098554

Catalytic subunit; deficiency = ALG13-CDG (X-linked developmental/epileptic encephalopathy). The ALG13 catalytic contribution is realised only in the ALG13/ALG14 UDP-GlcNAc transferase complex (GO:0043541), so for the gene product alone the activity is a contributes_to assertion.

ALG14: membrane-anchoring subunit
alg14_activity
Participant: Family: ALG14 family (membrane-anchoring subunit)
Family:
ALG14 family (membrane-anchoring subunit)PANTHER:PTHR12154
Representative Members: ALG14 (human)UniProtKB:Q96F25 ALG14 (Saccharomyces cerevisiae)UniProtKB:P38242 alg14 (Schizosaccharomyces pombe)UniProtKB:O14199

Function

protein-membrane adaptor activityGO:0043495
Substrates: ALG13 (catalytic subunit)
Products: ER-membrane-anchored ALG13/ALG14 transferase

Locations

endoplasmic reticulum membraneGO:0005789

Recruits/anchors catalytic ALG13 to the ER; the ALG13/ALG14 heterodimer forms the functional UDP-GlcNAc transferase. In S. cerevisiae ALG14 is reviewed as a non-catalytic subunit that contributes to GO:0004577 within the UDP-N-acetylglucosamine transferase complex (GO:0043541); the adaptor term captures the same membrane-recruitment role.

Part 3: first mannose (beta-1,4)
GlcNAc2-PP-dolichol to Man1GlcNAc2-PP-dolicholReactionalg1_step

Annotons

ALG1: beta-1,4-mannosyltransferase
alg1_activity
Participant: Family: ALG1 beta-mannosyltransferase family
Family:
ALG1 beta-mannosyltransferase family
Representative Members: ALG1 (human)UniProtKB:Q9BT22 ALG1 (Saccharomyces cerevisiae)UniProtKB:P16661 alg1 (Schizosaccharomyces pombe)UniProtKB:O13933

Function

chitobiosyldiphosphodolichol beta-mannosyltransferase activityGO:0004578
Substrates: GDP-mannose GlcNAc2-PP-dolichol
Products: Man1GlcNAc2-PP-dolichol GDP

Locations

cytoplasmic side of endoplasmic reticulum membraneGO:0098554

First mannose of the LLO; deficiency = ALG1-CDG (CDG-Ik).

Part 4: second and third mannoses (alpha-1,3 and alpha-1,6)
Man1GlcNAc2-PP-dolichol to Man3GlcNAc2-PP-dolicholReactionalg2_step

Annotons

ALG2: alpha-1,3/1,6-mannosyltransferase
alg2_activity
Participant: Family: ALG2 mannosyltransferase family
Family:
ALG2 mannosyltransferase familyPANTHER:PTHR45918
Representative Members: ALG2 (human)UniProtKB:Q9H553 ALG2 (Saccharomyces cerevisiae)UniProtKB:P43636 alg2 (Schizosaccharomyces pombe)UniProtKB:Q96WW6

Function

GDP-Man:Man(1)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activityGO:0004378
Substrates: GDP-mannose (x2) Man1GlcNAc2-PP-dolichol
Products: Man3GlcNAc2-PP-dolichol GDP

Locations

cytoplasmic side of endoplasmic reticulum membraneGO:0098554

Bifunctional; adds 2nd (alpha-1,3) and 3rd (alpha-1,6) mannoses. Deficiency = ALG2-CDG (CDG-Ii) and congenital myasthenic syndrome (CMS14).

Part 5: fourth and fifth mannoses (alpha-1,2) — completes Man5
Man3GlcNAc2-PP-dolichol to Man5GlcNAc2-PP-dolicholReactionalg11_step

Annotons

ALG11: alpha-1,2-mannosyltransferase
alg11_activity
Participant: Family: ALG11 mannosyltransferase family
Family:
ALG11 mannosyltransferase familyPANTHER:PTHR45919
Representative Members: ALG11 (human)UniProtKB:Q2TAA5 ALG11 (Saccharomyces cerevisiae)UniProtKB:P53954 alg11 (Schizosaccharomyces pombe)UniProtKB:O74878

Function

GDP-Man:Man(3)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activityGO:0004377
Substrates: GDP-mannose (x2) Man3GlcNAc2-PP-dolichol
Products: Man5GlcNAc2-PP-dolichol GDP

Locations

cytoplasmic side of endoplasmic reticulum membraneGO:0098554

Completes Man5GlcNAc2-PP-Dol, the final cytoplasmic-face LLO intermediate (then flipped to the lumen by RFT1). Deficiency = ALG11-CDG (CDG-Ip).