Enzymes
| UniProtKB help_outline | 3 proteins |
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- Name help_outline a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) Identifier CHEBI:57880 Charge -1 Formula C11H16O13PR2 SMILEShelp_outline [C@@H]1([C@@H]([C@@H]([C@@H]([C@H]([C@@H]1O)O)O)O)OP(OC[C@@H](COC(=O)*)OC(=O)*)(=O)[O-])O 2D coordinates Mol file for the small molecule Search links Involved in 74 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP-N-acetyl-α-D-glucosamine Identifier CHEBI:57705 (Beilstein: 4286654) help_outline Charge -2 Formula C17H25N3O17P2 InChIKeyhelp_outline LFTYTUAZOPRMMI-CFRASDGPSA-L SMILEShelp_outline CC(=O)N[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1OP([O-])(=O)OP([O-])(=O)OC[C@H]1O[C@H]([C@H](O)[C@@H]1O)n1ccc(=O)[nH]c1=O 2D coordinates Mol file for the small molecule Search links Involved in 88 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a 6-(N-acetyl-α-D-glucosaminyl)-1-phosphatidyl-1D-myo-inositol Identifier CHEBI:57265 Charge -1 Formula C19H29NO18PR2 SMILEShelp_outline CC(=O)N[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@@H]1[C@@H](O)[C@H](O)[C@@H](O)[C@@H](O)[C@H]1OP([O-])(=O)OC[C@@H](COC([*])=O)OC([*])=O 2D coordinates Mol file for the small molecule Search links Involved in 4 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,431 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP Identifier CHEBI:58223 Charge -3 Formula C9H11N2O12P2 InChIKeyhelp_outline XCCTYIAWTASOJW-XVFCMESISA-K SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])(=O)OP([O-])([O-])=O)O[C@H]([C@@H]1O)n1ccc(=O)[nH]c1=O 2D coordinates Mol file for the small molecule Search links Involved in 576 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:14789 | RHEA:14790 | RHEA:14791 | RHEA:14792 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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The first step of glycosylphosphatidylinositol biosynthesis is mediated by a complex of PIG-A, PIG-H, PIG-C and GPI1.
Watanabe R., Inoue N., Westfall B., Taron C.H., Orlean P., Takeda J., Kinoshita T.
Biosynthesis of glycosylphosphatidylinositol (GPI) is initiated by transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI). This chemically simple step is genetically complex because three genes are required in both mammals and yeast. Mammalian PIG-A and PIG-C are hom ... >> More
Biosynthesis of glycosylphosphatidylinositol (GPI) is initiated by transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI). This chemically simple step is genetically complex because three genes are required in both mammals and yeast. Mammalian PIG-A and PIG-C are homologous to yeast GPI3 and GPI2, respectively; however, mammalian PIG-H is not homologous to yeast GPI1. Here, we report cloning of a human homolog of GPI1 (hGPI1) and demonstrate that four mammalian gene products form a protein complex in the endoplasmic reticulum membrane. PIG-L, which is involved in the second step in GPI synthesis, GlcNAc-PI de-N-acetylation, did not associate with the isolated complex. The protein complex had GPI-GlcNAc transferase (GPI-GnT) activity in vitro, but did not mediate the second reaction. Bovine PI was utilized approximately 100-fold more efficiently than soybean PI as a substrate, and lyso PI was a very inefficient substrate. These results suggest that GPI-GnT recognizes the fatty acyl chains of PI. The unusually complex organization of GPI-GnT may be relevant to selective usage of PI and/or regulation. << Less
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The initial enzyme for glycosylphosphatidylinositol biosynthesis requires PIG-Y, a seventh component.
Murakami Y., Siripanyaphinyo U., Hong Y., Tashima Y., Maeda Y., Kinoshita T.
Biosynthesis of glycosylphosphatidylinositol (GPI) is initiated by an unusually complex GPI-N-acetylglucosaminyltransferase (GPI-GnT) consisting of at least six proteins. Here, we report that human GPI-GnT requires another component, termed PIG-Y, a 71 amino acid protein with two transmembrane dom ... >> More
Biosynthesis of glycosylphosphatidylinositol (GPI) is initiated by an unusually complex GPI-N-acetylglucosaminyltransferase (GPI-GnT) consisting of at least six proteins. Here, we report that human GPI-GnT requires another component, termed PIG-Y, a 71 amino acid protein with two transmembrane domains. The Burkitt lymphoma cell line Daudi, severely defective in the surface expression of GPI-anchored proteins, was a null mutant of PIG-Y. A complex of six components was formed without PIG-Y. PIG-Y appeared to be directly associated with PIG-A, implying that PIG-Y is the key molecule that regulates GPI-GnT activity by binding directly to the catalytic subunit PIG-A. PIG-Y is probably homologous to yeast Eri1p, a component of GPI-GnT. We did not obtain evidence for a functional linkage between GPI-GnT and ras GTPases in mammalian cells as has been reported for yeast cells. A single transcript encoded PIG-Y and, to its 5' side, another protein PreY that has homologues in a wide range of organisms and is characterized by a conserved domain termed DUF343. These two proteins are translated from one mRNA by leaky scanning of the PreY initiation site. << Less