Pathway: GPI-ANCHOR PROTEIN BIOSYNTHESIS

General Information

Name

GPI-ANCHOR PROTEIN BIOSYNTHESIS

Species

D. melanogaster

Symbol

GPIANB

FlyBase ID

FBgg0002150

Date last reviewed

2025-08-03

Number of members

Description

The biosynthesis of glycosylphosphatidylinositol (GPI)-anchor proteins involves 3 steps: (1) the assembly of the GPI-anchor, which occurs in the endoplasmic reticulum (ER), and involves the sequential addition of a glucosamine, an acyl chain and 3 or 4 mannose residues (each modified with phosphoethanolamine, pEtn) to the inositol head group of phosphatidylinositol; (2) the attachment of the GPI-anchor to the protein carboxyl terminus via an amide bond to the last pEtn by the GPI transamidase complex; and (3) the post-attachment modifications of the GPI-anchor, which occur in the ER and Golgi apparatus and involve the removal of the 2nd mannose-linked pEtn and the inositol-linked acyl chain, followed by the remodeling of the fatty acid chains. The mature GPI-anchor proteins are transported to the plasma membrane. (Adapted from FBrf0220328 and PMID:32156170.)

Notes

In D. melanogaster, the fatty acid chain remodelling occurring prior and after the attachment of the GPI-anchor to the proteins is not documented. It is also not known whether the GPI-anchor glycan core can be further modified with attachment of additional sugars. PIG-Wb is a paralog of PIG-Wa and is specifically expressed in the midgut. CG4907, CG13978, CG5342 and CG6790 are paralogs of PIG-N and are specifically expressed in testis. As there is no functional information, CG4907, CG13978, CG5342 and CG6790 are not included in the gene list. CG7990 and CG15880 are paralogs of PGAP2 and are expressed in the brain and the testis, respectively. As there is no functional information, CG7990 and CG15880 are not included in the gene list.