title: Sorting of GPI-anchored proteins into ER exit sites by p24 proteins is dependent on remodeled GPI.
abstract: Glycosylphosphatidylinositol (GPI) anchoring of proteins is a posttranslational modification occurring in the endoplasmic reticulum (ER). After GPI attachment, proteins are transported by coat protein complex II (COPII)-coated vesicles from the ER. Because GPI-anchored proteins (GPI-APs) are localized in the lumen, they cannot interact with cytosolic COPII components directly. Receptors that link GPI-APs to COPII are thought to be involved in efficient packaging of GPI-APs into vesicles; however, mechanisms of GPI-AP sorting are not well understood. Here we describe two remodeling reactions for GPI anchors, mediated by PGAP1 and PGAP5, which were required for sorting of GPI-APs to ER exit sites. The p24 family of proteins recognized the remodeled GPI-APs and sorted them into COPII vesicles. Association of p24 proteins with GPI-APs was pH dependent, which suggests that they bind in the ER and dissociate in post-ER acidic compartments. Our results indicate that p24 complexes act as cargo receptors for correctly remodeled GPI-APs to be sorted into COPII vesicles.
authors: Research Institute for Microbial Diseases and WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
authors: Morihisa
authors: M
authors: Fujita
authors: Reika
authors: R
authors: Watanabe
authors: Nina
authors: N
authors: Jaensch
authors: Maria
authors: M
authors: Romanova-Michaelides
authors: Tadashi
authors: T
authors: Satoh
authors: Masaki
authors: M
authors: Kato
authors: Howard
authors: H
authors: Riezman
authors: Yoshiki
authors: Y
authors: Yamaguchi
authors: Yusuke
authors: Y
authors: Maeda
authors: Taroh
authors: T
authors: Kinoshita
mesh_terms: D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D058851:GPI-Linked Proteins / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D008954:Models, Biological; D020133:Reverse Transcriptase Polymerase Chain Reaction; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: D058851:GPI-Linked Proteins; D017261:Glycosylphosphatidylinositols; D033921:Vesicular Transport Proteins