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PIG-M transfers the first mannose to glycosylphosphatidylinositol on the lumenal side of the ER.

Authors: Maeda, Y  Watanabe, R  Harris, CL  Hong, Y  Ohishi, K  Kinoshita, K  Kinoshita, T 
Citation: Maeda Y, etal., EMBO J 2001 Jan 15;20(1-2):250-61.
Pubmed: (View Article at PubMed) PMID:11226175
DOI: Full-text: DOI:10.1093/emboj/20.1.250

Glycosylphosphatidylinositol (GPI) acts as a membrane anchor of many cell surface proteins. Its structure and biosynthetic pathway are generally conserved among eukaryotic organisms, with a number of differences. In particular, mammalian and protozoan mannosyltransferases needed for addition of the first mannose (GPI-MT-I) have different substrate specificities and are targets of species- specific inhibitors of GPI biosynthesis. GPI-MT-I, however, has not been molecularly characterized. Characterization of GPI-MT-I would also help to clarify the topology of GPI biosynthesis. Here, we report a human cell line defective in GPI-MT-I and the gene responsible, PIG-M. PIG-M encodes a new type of mannosyltransferase of 423 amino acids, bearing multiple transmembrane domains. PIG-M has a functionally important DXD motif, a characteristic of many glycosyltransferases, within a domain facing the lumen of the endoplasmic reticulum (ER), indicating that transfer of the first mannose to GPI occurs on the lumenal side of the ER membrane.


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CRRD Object Information
CRRD ID: 70624
Created: 2002-06-11
Species: All species
Last Modified: 2002-06-18
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.