Post-translational modification: synthesis of GPI-anchored proteins (Homo sapiens)

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Glycosylphosphatidyl inositol (GPI) acts as a membrane anchor for many cell surface proteins. GPI is synthesized in the endoplasmic reticulum. In humans, a single pathway consisting of eleven reactions appears to be responsible for the synthesis of the major GPI species involved in membrane protein anchoring.

As a nascent protein fated to become GPI-anchored moves into the lumen of the endoplasmic reticulum, it is attacked by a transamidase complex that cleaves it near its carboxy terminus and attaches an acylated GPI moiety. The GPI moiety is deacylated, yielding a protein-GPI conjugate that can be efficiently transported to the Golgi apparatus.Original Pathway at Reactome: http://www.reactome.org/PathwayBrowser/#DB=gk_current&FOCUS_SPECIES_ID=48887&FOCUS_PATHWAY_ID=163125</div>

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Bibliography

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1. Taron BW, Colussi PA, Wiedman JM, Orlean P, Taron CH.; ''Human Smp3p adds a fourth mannose to yeast and human glycosylphosphatidylinositol precursors in vivo.''; PubMed Europe PMC Scholia
2. Watanabe R, Kinoshita T, Masaki R, Yamamoto A, Takeda J, Inoue N.; ''PIG-A and PIG-H, which participate in glycosylphosphatidylinositol anchor biosynthesis, form a protein complex in the endoplasmic reticulum.''; PubMed Europe PMC Scholia
3. Schofield JN, Rademacher TW.; ''Structure and expression of the human glycosylphosphatidylinositol phospholipase D1 (GPLD1) gene.''; PubMed Europe PMC Scholia
4. Murakami Y, Siripanyaphinyo U, Hong Y, Tashima Y, Maeda Y, Kinoshita T.; ''The initial enzyme for glycosylphosphatidylinositol biosynthesis requires PIG-Y, a seventh component.''; PubMed Europe PMC Scholia
5. Takahashi M, Inoue N, Ohishi K, Maeda Y, Nakamura N, Endo Y, Fujita T, Takeda J, Kinoshita T.; ''PIG-B, a membrane protein of the endoplasmic reticulum with a large lumenal domain, is involved in transferring the third mannose of the GPI anchor.''; PubMed Europe PMC Scholia
6. Kang JY, Hong Y, Ashida H, Shishioh N, Murakami Y, Morita YS, Maeda Y, Kinoshita T.; ''PIG-V involved in transferring the second mannose in glycosylphosphatidylinositol.''; PubMed Europe PMC Scholia
7. Maeda Y, Tanaka S, Hino J, Kangawa K, Kinoshita T.; ''Human dolichol-phosphate-mannose synthase consists of three subunits, DPM1, DPM2 and DPM3.''; PubMed Europe PMC Scholia
8. Watanabe R, Murakami Y, Marmor MD, Inoue N, Maeda Y, Hino J, Kangawa K, Julius M, Kinoshita T.; ''Initial enzyme for glycosylphosphatidylinositol biosynthesis requires PIG-P and is regulated by DPM2.''; PubMed Europe PMC Scholia
9. Pottekat A, Menon AK.; ''Subcellular localization and targeting of N-acetylglucosaminyl phosphatidylinositol de-N-acetylase, the second enzyme in the glycosylphosphatidylinositol biosynthetic pathway.''; PubMed Europe PMC Scholia
10. Murakami Y, Siripanyapinyo U, Hong Y, Kang JY, Ishihara S, Nakakuma H, Maeda Y, Kinoshita T.; ''PIG-W is critical for inositol acylation but not for flipping of glycosylphosphatidylinositol-anchor.''; PubMed Europe PMC Scholia
11. Davitz MA, Hereld D, Shak S, Krakow J, Englund PT, Nussenzweig V.; ''A glycan-phosphatidylinositol-specific phospholipase D in human serum.''; PubMed Europe PMC Scholia
12. Fabre AL, Orlean P, Taron CH.; ''Saccharomyces cerevisiae Ybr004c and its human homologue are required for addition of the second mannose during glycosylphosphatidylinositol precursor assembly.''; PubMed Europe PMC Scholia
13. Shishioh N, Hong Y, Ohishi K, Ashida H, Maeda Y, Kinoshita T.; ''GPI7 is the second partner of PIG-F and involved in modification of glycosylphosphatidylinositol.''; PubMed Europe PMC Scholia
14. Low MG, Prasad AR.; ''A phospholipase D specific for the phosphatidylinositol anchor of cell-surface proteins is abundant in plasma.''; PubMed Europe PMC Scholia
15. Hong Y, Ohishi K, Kang JY, Tanaka S, Inoue N, Nishimura J, Maeda Y, Kinoshita T.; ''Human PIG-U and yeast Cdc91p are the fifth subunit of GPI transamidase that attaches GPI-anchors to proteins.''; PubMed Europe PMC Scholia
16. Ohishi K, Inoue N, Kinoshita T.; ''PIG-S and PIG-T, essential for GPI anchor attachment to proteins, form a complex with GAA1 and GPI8.''; PubMed Europe PMC Scholia
17. Ashida H, Hong Y, Murakami Y, Shishioh N, Sugimoto N, Kim YU, Maeda Y, Kinoshita T.; ''Mammalian PIG-X and yeast Pbn1p are the essential components of glycosylphosphatidylinositol-mannosyltransferase I.''; PubMed Europe PMC Scholia
18. Sharma DK, Smith TK, Weller CT, Crossman A, Brimacombe JS, Ferguson MA.; ''Differences between the trypanosomal and human GlcNAc-PI de-N-acetylases of glycosylphosphatidylinositol membrane anchor biosynthesis.''; PubMed Europe PMC Scholia
19. Kinoshita T, Inoue N.; ''Dissecting and manipulating the pathway for glycosylphos-phatidylinositol-anchor biosynthesis.''; PubMed Europe PMC Scholia
20. Watanabe R, Inoue N, Westfall B, Taron CH, Orlean P, Takeda J, Kinoshita T.; ''The first step of glycosylphosphatidylinositol biosynthesis is mediated by a complex of PIG-A, PIG-H, PIG-C and GPI1.''; PubMed Europe PMC Scholia
21. Maeda Y, Watanabe R, Harris CL, Hong Y, Ohishi K, Kinoshita K, Kinoshita T.; ''PIG-M transfers the first mannose to glycosylphosphatidylinositol on the lumenal side of the ER.''; PubMed Europe PMC Scholia
22. Yu J, Nagarajan S, Knez JJ, Udenfriend S, Chen R, Medof ME.; ''The affected gene underlying the class K glycosylphosphatidylinositol (GPI) surface protein defect codes for the GPI transamidase.''; PubMed Europe PMC Scholia
23. Gaynor EC, Mondésert G, Grimme SJ, Reed SI, Orlean P, Emr SD.; ''MCD4 encodes a conserved endoplasmic reticulum membrane protein essential for glycosylphosphatidylinositol anchor synthesis in yeast.''; PubMed Europe PMC Scholia

History

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Compare	Revision	Action	Time	User	Comment
	114905	view	16:42, 25 January 2021	ReactomeTeam	Reactome version 75
	113350	view	11:42, 2 November 2020	ReactomeTeam	Reactome version 74
	112559	view	15:52, 9 October 2020	ReactomeTeam	Reactome version 73
	101472	view	11:33, 1 November 2018	ReactomeTeam	reactome version 66
	101010	view	21:13, 31 October 2018	ReactomeTeam	reactome version 65
	100546	view	19:47, 31 October 2018	ReactomeTeam	reactome version 64
	100094	view	16:32, 31 October 2018	ReactomeTeam	reactome version 63
	99644	view	15:03, 31 October 2018	ReactomeTeam	reactome version 62 (2nd attempt)
	99246	view	12:44, 31 October 2018	ReactomeTeam	reactome version 62
	93983	view	13:49, 16 August 2017	ReactomeTeam	reactome version 61
	93587	view	11:28, 9 August 2017	ReactomeTeam	reactome version 61
	88102	view	09:33, 26 July 2016	Ryanmiller	Ontology Term : 'peptide and protein metabolic process' added !
	88101	view	09:31, 26 July 2016	Ryanmiller	Ontology Term : 'classic metabolic pathway' added !
	86827	view	08:17, 12 July 2016	MaintBot	CHEBI:53058 is a Metabolite in ChEBI (which partially defined structure)
	86695	view	09:24, 11 July 2016	ReactomeTeam	reactome version 56
	83233	view	10:26, 18 November 2015	ReactomeTeam	Version54
	81631	view	13:10, 21 August 2015	ReactomeTeam	Version53
	80028	view	09:40, 1 May 2015	Egonw	Renamed 1,2-Diacylglyceroll to 1,2-Diacylglycerol.
	77093	view	08:39, 17 July 2014	ReactomeTeam	Fixed remaining interactions
	76799	view	12:18, 16 July 2014	ReactomeTeam	Fixed remaining interactions
	76122	view	10:18, 11 June 2014	ReactomeTeam	Re-fixing comment source
	75834	view	11:40, 10 June 2014	ReactomeTeam	Reactome 48 Update
	75194	view	09:41, 9 May 2014	Anwesha
	74840	view	10:06, 30 April 2014	ReactomeTeam	Reactome46
	68929	view	17:33, 8 July 2013	MaintBot	Updated to 2013 gpml schema
	42103	view	21:57, 4 March 2011	MaintBot	Automatic update
	39913	view	05:56, 21 January 2011	MaintBot	New pathway

External references

DataNodes

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Name	Type	Database reference	Comment
(ethanolamineP) mannose (a1-2) (ethanolamineP) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		G00151 (KEGG Glycan)
(ethanolamineP) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		G00150 (KEGG Glycan)
(ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		REACT_2468 (Reactome)
1,2-Diacylglyceroll		CHEBI:17815 (ChEBI)
CH3COO-	Metabolite	CHEBI:15366 (ChEBI)
CoA-SH	Metabolite	CHEBI:15346 (ChEBI)
DOLP	Metabolite	CHEBI:16214 (ChEBI)
DOLPM	Metabolite	CHEBI:15809 (ChEBI)
DOLPman		CHEBI:15809 (ChEBI)
DPM1 [endoplasmic reticulum membrane]	Protein	O60762 (Uniprot-TrEMBL)
DPM1,2,3	Complex	REACT_3881 (Reactome)
DPM2 [endoplasmic reticulum membrane]	Protein	O94777 (Uniprot-TrEMBL)
DPM3 [endoplasmic reticulum membrane]	Protein	Q9P2X0 (Uniprot-TrEMBL)
Fatty acyl CoA		CHEBI:37554 (ChEBI)
GDP-Man	Metabolite	CHEBI:15820 (ChEBI)
GPAA1 [endoplasmic reticulum membrane]	Protein	O43292 (Uniprot-TrEMBL)
GPI mannosyltransferase I	Complex	REACT_2364 (Reactome)
GPI transamidase	Complex	REACT_4592 (Reactome)
GPI-N-acetylglucosaminyltransferase	Complex	REACT_5237 (Reactome)
H2O	Metabolite	CHEBI:15377 (ChEBI)
Long-chain fatty acid		CHEBI:15904 (ChEBI)
N-acetylglucosaminyl-PI		CHEBI:15935 (ChEBI)
N-glycyl-glycosylphosphatidylinositolethanolamine-PLAUR	Protein	Q03405 (Uniprot-TrEMBL)
PE		CHEBI:16038 (ChEBI)
PGAP1	Protein	Q75T13 (Uniprot-TrEMBL)
PIG-F:GPI7 complex	Complex	REACT_5313 (Reactome)
PIG-F:PIG-O complex	Complex	REACT_5770 (Reactome)
PIGA [endoplasmic reticulum membrane]	Protein	P37287 (Uniprot-TrEMBL)
PIGB	Protein	Q92521 (Uniprot-TrEMBL)
PIGC [endoplasmic reticulum membrane]	Protein	Q92535 (Uniprot-TrEMBL)
PIGF [endoplasmic reticulum membrane]	Protein	Q07326 (Uniprot-TrEMBL)
PIGG [endoplasmic reticulum membrane]	Protein	Q5H8A4 (Uniprot-TrEMBL)
PIGH [endoplasmic reticulum membrane]	Protein	Q14442 (Uniprot-TrEMBL)
PIGK [endoplasmic reticulum membrane]	Protein	Q92643 (Uniprot-TrEMBL)
PIGL	Protein	Q9Y2B2 (Uniprot-TrEMBL)
PIGM [endoplasmic reticulum membrane]	Protein	Q9H3S5 (Uniprot-TrEMBL)
PIGN	Protein	O95427 (Uniprot-TrEMBL)
PIGO [endoplasmic reticulum membrane]	Protein	Q8TEQ8 (Uniprot-TrEMBL)
PIGP(26-158) [endoplasmic reticulum membrane]	Protein	P57054 (Uniprot-TrEMBL)
PIGQ-2 [endoplasmic reticulum membrane]	Protein	Q9BRB3-2 (Uniprot-TrEMBL)
PIGS [endoplasmic reticulum membrane]	Protein	Q96S52 (Uniprot-TrEMBL)
PIGT [endoplasmic reticulum membrane]	Protein	Q969N2 (Uniprot-TrEMBL)
PIGU [endoplasmic reticulum membrane]	Protein	Q9H490 (Uniprot-TrEMBL)
PIGV	Protein	Q9NUD9 (Uniprot-TrEMBL)
PIGW	Protein	Q7Z7B1 (Uniprot-TrEMBL)
PIGX [endoplasmic reticulum membrane]	Protein	Q8TBF5 (Uniprot-TrEMBL)
PLAUR(23-335)	Protein	Q03405 (Uniprot-TrEMBL)
PLAUR(306-335)	Protein	Q03405 (Uniprot-TrEMBL)
PLAUR	Protein	Q03405 (Uniprot-TrEMBL)
SMP3	Protein	Q9H9G5 (Uniprot-TrEMBL)
UDP-AcGlcN	Metabolite	CHEBI:16264 (ChEBI)
UDP	Metabolite	CHEBI:17659 (ChEBI)
dolichyl phosphate		CHEBI:16214 (ChEBI)
glucosaminyl-PI		CHEBI:24275 (ChEBI)
glucosaminyl-acyl-PI		CHEBI:52572 (ChEBI)
mannose (a1) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		REACT_2710 (Reactome)
mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		CHEBI:53059 (ChEBI)
mannose (a1-4) glucosaminyl-acyl-PI		CHEBI:53056 (ChEBI)
mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI		CHEBI:53058 (ChEBI)
phosphatidylinositol		CHEBI:16749 (ChEBI)

Annotated Interactions

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Source	Target	Type	Database reference	Comment
	(ethanolamineP) mannose (a1-2) (ethanolamineP) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_155 (Reactome)
	(ethanolamineP) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_2043 (Reactome)
(ethanolamineP) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_155 (Reactome)
(ethanolamineP) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_1777 (Reactome)
	(ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_464 (Reactome)
(ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_1848 (Reactome)
	1,2-Diacylglyceroll	Arrow	REACT_2043 (Reactome)
	1,2-Diacylglyceroll	Arrow	REACT_464 (Reactome)
	CH3COO-	Arrow	REACT_779 (Reactome)
	CoA-SH	Arrow	REACT_1049 (Reactome)
	DOLPM	Arrow	REACT_652 (Reactome)
DOLP			REACT_2036 (Reactome)
	DOLPman	Arrow	REACT_2036 (Reactome)
DOLPman			REACT_1018 (Reactome)
DOLPman			REACT_1308 (Reactome)
DOLPman			REACT_1848 (Reactome)
DOLPman			REACT_2179 (Reactome)
DOLPman			REACT_652 (Reactome)
DPM1,2,3		mim-catalysis	REACT_2036 (Reactome)
Fatty acyl CoA			REACT_1049 (Reactome)
GDP-Man			REACT_2036 (Reactome)
GPI mannosyltransferase I		mim-catalysis	REACT_1018 (Reactome)
GPI transamidase		mim-catalysis	REACT_1777 (Reactome)
GPI-N-acetylglucosaminyltransferase		mim-catalysis	REACT_1240 (Reactome)
H2O			REACT_1978 (Reactome)
H2O			REACT_779 (Reactome)
	Long-chain fatty acid	Arrow	REACT_1978 (Reactome)
	N-acetylglucosaminyl-PI	Arrow	REACT_1240 (Reactome)
N-acetylglucosaminyl-PI			REACT_779 (Reactome)
	N-glycyl-glycosylphosphatidylinositolethanolamine-PLAUR	Arrow	REACT_1777 (Reactome)
N-glycyl-glycosylphosphatidylinositolethanolamine-PLAUR			REACT_1978 (Reactome)
PE			REACT_2043 (Reactome)
PE			REACT_464 (Reactome)
PGAP1		mim-catalysis	REACT_1978 (Reactome)
PIG-F:GPI7 complex		mim-catalysis	REACT_155 (Reactome)
PIG-F:PIG-O complex		mim-catalysis	REACT_2043 (Reactome)
PIGB		mim-catalysis	REACT_1308 (Reactome)
PIGL		mim-catalysis	REACT_779 (Reactome)
PIGN		mim-catalysis	REACT_464 (Reactome)
PIGV		mim-catalysis	REACT_1848 (Reactome)
PIGW		mim-catalysis	REACT_1049 (Reactome)
PLAUR(23-335)			REACT_1777 (Reactome)
	PLAUR(306-335)	Arrow	REACT_1777 (Reactome)
	PLAUR	Arrow	REACT_1978 (Reactome)
			REACT_1018 (Reactome)	In the fifth step of GPI synthesis, a mannose residue is added to glucosaminyl-acyl-PI. The reaction takes place at the lumenal surface of the endoplasmic reticulum membrane. It is catalyzed by a complex of at least two components, PIG-M and PIG-X (Maeda et al. 2001; Ashida et al. 2005).
			REACT_1049 (Reactome)	In the fourth step of GPI synthesis, an acyl group (typically palmitate) is transferred from acyl CoA to glucosaminyl-PI. Mutagenesis and cloning studies suggest that a single protein, PIG-W, catalyzes this reaction (Murakami et al. 2003).
			REACT_1240 (Reactome)	The first step of GPI synthesis is the transfer of N-acetylglucosamine from cytosolic UDP-N-acetylglucosamine to phosphatidyl inositol (PI) in the endoplasmic reticulum membrane. The reaction is catalyzed by a multimeric enzyme, also localized to the endoplasmic reticulum membrane, six components of which have been identified to date by mutagenesis studies in cultured cells and by co-recipitation studies in vitro (Watanabe et al. 1996, 1998, 2000).
			REACT_1308 (Reactome)	In the eighth reaction of GPI synthesis, a third mannose residue is added, catalyzed by PIG-B (Takahashi et al. 1996).
			REACT_1526 (Reactome)	GPI moieties are synthesized anchored to dolichol phosphate in the membrane of the endoplasmic reticulum. The first two steps of the synthetic pathway, leading to the production of glucosaminyl-PI, occur on the cytosolic face of the membrane, while addition of an acyl group (step 4) and all subsequent steps occur on the lumenal face (Murakami et al. 2003). No mutant cell lines defective in the reorientation step have been identified, and the mechanism by which it occurs is unknown.
			REACT_155 (Reactome)	Most human GPI anchors have ethanolamine phosphate groups attached to their first and third mannose residues, but GPI anchors with ethanolamine phosphates attached to all three mannose residues have also been identified. Addition of the third ethanolamine phosphate can be catalyzed by a complex of PIG-F and a newly described human protein, GPI7. The donor of the ethanolamine phosphate for this reaction is unknown (Shishioh et al. 2005).
			REACT_1777 (Reactome)	In the endoplasmic reticulum, the precursor form of urokinase plasminogen activator receptor is transamidated at residue 305, replacing the 30 carboxyterminal residues of the protein with an acylated glucosylphosphatidylinositol (acyl-GPI) moiety. The released carboxyterminal propeptide has no known function. The reaction is catalyzed by GPI transamidase, a complex of at least five proteins associated with the lumenal surface of the endoplasmic reticulum membrane (Yu et al. 1997; Ohishi et al. 2001; Hong et al. 2003).
			REACT_1848 (Reactome)	In the seventh reaction of GPI synthesis, a second mannose residue is added to the glycolipid on the lumenal face of the endoplasmic reticulum membrane. PIG-V was identified as the catylyst, or a component of the catalyst, of this reaction, on the basis of its ability to correct the metabolic defects of yeast and mammalian mutant cells arrested at this stage of the GPI synthetic process (Fabre et al. 2005; Kang et al. 2005).
			REACT_1978 (Reactome)	The fatty acid group added to inositol in the fourth step of GPI biosynthsis is removed from GPI-conjugated uPAR. This hydrolysis event occurs in the endoplasmic reticulum and appears to be associated with efficient transport of the conjugated protein from the endoplasmic reticulum to the Golgi apparatus (Tanaka et al. 2004).
			REACT_2036 (Reactome)	Cytosolic GDP-mannose reacts with dolichyl phosphate in the endoplasmic reticulum membrane to form dolichyl phosphate D-mannose. The reaction is catalyzed by dolichyl-phosphate mannosyltransferase, a heterotrimeric protein embedded in the endoplasmic reticulum membrane. The first subunit of the heterotrimer appears to be the actual catalyst, and the other two subunits appear to stabilize it (Maeda et al. 2000).
			REACT_2043 (Reactome)	The final step in the main pathway for the synthesis of GPI moieties in human cells is the addition of an ethanolamine phosphate to the third mannose residue of the glycolipid, donated by phosphatidylethanolamine. This reaction has been experimentally characterized in the mouse, where studies with mutated cell lines defective in GPI biosynthesis have established the role of two proteins, PIG-F and PIG-O, in this reaction (Hong et al. 2000). While a human PIG-F protein has been identified and shown to be involved in this event (Inoue et al. 1993), the human event has not been fully characterized and is therefore annotated here as inferred from studies of the mouse event.
			REACT_2179 (Reactome)	Most human GPI anchors are thought to contain three mannose residues, while most yeast GPI anchors contain four. Recently, a human homologue of the yeast enzyme responsible for addition of the fourth mannose residue to GPI molecules was identified and shown to mediate synthesis of human GPI molecules with four mannose residues. While the mannose donor and the nature of the bond linking the third and fourth mannose residues have not been established directly in studies with the human enzyme, these features are known for yeast and the normal human gene restores GPI synthesis in mutant yeast. This observation, tegether with the sequence similarities among PIG-B and SMP3, it is reasonable to infer that the human enzyme uses dolichol-P-mannose as a donor. The functional distinction between GPI anchors with three and four mannose residues is unknown, although the latter appear to be abundant in many human tissues (Tauron et al. 2004).
			REACT_464 (Reactome)	In the sixth step of GPI synthesis, a phosphoethanolamine group is transferred from phosphatidylethanolamine onto the first mannose of the GPI precursor. The human protein that catalyzes this reaction was first identified because it could complement a yeast mutant strain defective for GPI synthesis (Gaynor et al. 1999); its specific function in phosphoethanolamine transfer is inferred from functional studies of the homologous mouse protein (Hong et al. 1999). The reaction is annotated here with phosphatidylethanolamine as the donor of the phosphoethanolamine group on the basis of studies in yeast (Imhof et al. 2000).
			REACT_652 (Reactome)	Dolichyl phosphate D-mannose is flipped in the endoplasmic reticulum membrane so that its mannose moiety is oriented inwards, towards the endoplasmic reticulum lumen, where it is accessible to transferases catalyzing the synthesis of glycolipids and glycoproteins (Kinoshita and Inoue 2000).
			REACT_779 (Reactome)	In the second step of GPI synthesis, N-acetylglucosaminyl-PI is hydrolyzed to yield glucosaminyl-PI and acetate. The phosphatidylinositol (PI) derivatives involved in this reaction are located in the endoplasmic reticulum membrane, as is the PIG-L enzyme that catalyzes it (Sharma et al. 1999; Pottekat and Menon 2004).
SMP3		mim-catalysis	REACT_2179 (Reactome)
UDP-AcGlcN			REACT_1240 (Reactome)
	UDP	Arrow	REACT_1240 (Reactome)
	dolichyl phosphate	Arrow	REACT_1018 (Reactome)
	dolichyl phosphate	Arrow	REACT_1308 (Reactome)
	dolichyl phosphate	Arrow	REACT_1848 (Reactome)
	glucosaminyl-PI	Arrow	REACT_779 (Reactome)
glucosaminyl-PI			REACT_1049 (Reactome)
	glucosaminyl-acyl-PI	Arrow	REACT_1049 (Reactome)
	glucosaminyl-acyl-PI	Arrow	REACT_1526 (Reactome)
glucosaminyl-acyl-PI			REACT_1018 (Reactome)
glucosaminyl-acyl-PI			REACT_1526 (Reactome)
	mannose (a1) mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_2179 (Reactome)
	mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_1308 (Reactome)
mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_2043 (Reactome)
mannose (a1-2) mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_2179 (Reactome)
	mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_1018 (Reactome)
mannose (a1-4) glucosaminyl-acyl-PI			REACT_464 (Reactome)
	mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI	Arrow	REACT_1848 (Reactome)
mannose (a1-6) (ethanolamineP) mannose (a1-4) glucosaminyl-acyl-PI			REACT_1308 (Reactome)
phosphatidylinositol			REACT_1240 (Reactome)