PIG-B, GPI-Man Transferase III, Man- (Ethanolaminephosphate)Man-GlcN- (Acy1)PI Mannosyltransferase
The core backbone of the glycosylphosphatidylinositol (GPI) anchors contains three mannoses, each linked in different bonds. All three mannoses are donated by dolichol- phosphate-mannose. Three dolichol-phosphate-mannose-dependent mannosyltrans- ferases are therefore involved in biosynthesis of the GPI-anchors. PIG-B is necessary for transfer of the third mannose and is most likely α1,2-mannosyltransferase itself. PIG-B cDNA was expression-cloned using a mouse mutant cell line that is defective in transfer of the third mannose to GPI. PIG-B encodes a 554-amino-acid protein expressed in the endoplasmic reticulum (ER), where GPI is assembled. It has multiple hydrophobic regions, some of which may be transmembrane domains.
KeywordsEndoplasmic Reticulum Trypanosoma Brucei Acceptor Substrate Endoplasmic Reticulum Lumen Phospho Ethanolamine
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