<i>N</i>-Glycan–dependent protein folding and endoplasmic reticulum retention regulate GPI-anchor processing

Liu, Yi-Shi; Guo, Xinyu; Hirata, Tetsuya; Yao, Rong; Motooka, Daisuke; Kitajima, Toshihiko; Murakami, Yoshiko; Gao, Xiao‐Dong; Nakamura, Shota; Kinoshita, Taroh; Fujita, Morihisa

doi:10.1083/jcb.201706135

Cited by 60 publications

(67 citation statements)

References 55 publications

(79 reference statements)

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“…Calnexin was observed to associate with CD59 in an N-glycan-and GPI-dependent manner (Figure S2 C), as previously observed (22). ERp57 weakly co-precipitated with CD59 and misfolded CD59, whereas interactions with other ER chaperones, such as calreticulin and BiP, were not detected with any CD59 construct (Figure S2 C), indicating that the N-glycan and membrane-associated domain of GPI-APs are important for calnexin interaction.…”

Section: Glycan Binding Of Calnexin Is Required For Efficient Gpi-inosupporting

confidence: 80%

“…If an acylchain is attached to the 2-position of the inositol, PI-PLC cannot cleave the substrate ( Figure 1A). We previously demonstrated that GPI-inositol deacylation of CD59 and CD55 is partially impaired in cells defective for calnexin (CANX) and is more strongly affected in cells defective for both CANX and calreticulin (CALR) (22). To determine if the CANX/CALR-dependency of GPI-inositol diacylation is a general phenomenon of various GPI-APs, we treated CANX&CALR-DKO HEK293 cells with PI-PLC, and endogenous CD59, CD55, and CD109 in the CANX&CALR-DKO cells showed PI-PLC resistance ( Figure 1B and C).…”

Section: Calnexin/calreticulin Cycle Is Required For Efficient Gpi-inmentioning

confidence: 99%

“…Approximately 95% of GPI-APs in mammalian cells contain at least one N-glycan (22). To determine whether calnexin/calreticulin also affects the inositol-deacylation of non-Nglycosylated GPI-APs, we analyzed LY6D and GFP-GPI, which have no N-glycan, by PI-PLC treatment in WT and CANX&CALR-DKO cells.…”

Section: Calnexin/calreticulin Cycle Is Required For Efficient Gpi-inmentioning

confidence: 99%

“…In our previous study, we performed a genetic screening to identify factors that affect GPIinositol deacylation. In the screening, MOGS, GANAB, and CANX, as well as PGAP1, were identified as candidates (22). MOGS, GANAB, and CANX encode α-glucosidase I and II and calnexin, respectively (23).…”

Section: Introductionmentioning

confidence: 99%

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Calnexin mediates the maturation of GPI-anchors through ER retention

Guo

Liu

Gao

et al. 2020

Journal of Biological Chemistry

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The protein folding and lipid moiety status of glycosylphosphatidylinositol-anchored proteins (GPI-APs) are monitored in the endoplasmic reticulum (ER), with calnexin playing dual roles in the maturation of GPI-APs. In the present study, we investigated the functions of calnexin in the quality control and lipid remodeling of GPI-APs in the ER. By directly binding the N-glycan on proteins, calnexin was observed to efficiently retain GPI-APs in the ER until they were correctly folded. In addition, sufficient ER retention time was crucial for GPI-inositol deacylation, which is mediated by post-GPI attachment protein 1 (PGAP1). Once the calnexin/calreticulin cycle was disrupted, misfolded and inositol-acylated GPI-APs could not be retained in the ER and were exposed on the plasma membrane. In calnexin/calreticulin deficient cells, endogenous GPI-anchored alkaline phosphatase was expressed on the cell surface, but its activity was significantly decreased. ER stress induced surface expression of misfolded GPI-APs, but proper GPI-inositol deacylation occurred due to the extended time that they were retained in the ER. Our results indicate that calnexin-mediated ER quality control systems for GPI-APs are necessary for both protein folding and GPI-inositol deacylation.

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Section: Glycan Binding Of Calnexin Is Required For Efficient Gpi-inosupporting

confidence: 80%

Section: Calnexin/calreticulin Cycle Is Required For Efficient Gpi-inmentioning

confidence: 99%

Section: Calnexin/calreticulin Cycle Is Required For Efficient Gpi-inmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Calnexin mediates the maturation of GPI-anchors through ER retention

Guo

Liu

Gao

et al. 2020

Journal of Biological Chemistry

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“…During the transport through the secretory pathway, misfolded GPI-APs are escorted by ER-derived chaperones, such as BiP and calnexin, and p24 proteins [116]. Most GPI-APs have at least one N-glycan and their folding is mediated by N-glycan-dependent calnexin cycle [117]. Calnexin also binds to PGAP1 and facilitates PGAP1-mediated removal of the acyl chain from inositol [117].…”

Section: Quality Control Of Gpi-apsmentioning

confidence: 99%

Biosynthesis and biology of mammalian GPI-anchored proteins

2020

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At least 150 human proteins are glycosylphosphatidylinositol-anchored proteins (GPI-APs). The protein moiety of GPI-APs lacking transmembrane domains is anchored to the plasma membrane with GPI covalently attached to the C-terminus. The GPI consists of the conserved core glycan, phosphatidylinositol and glycan side chains. The entire GPI-AP is anchored to the outer leaflet of the lipid bilayer by insertion of fatty chains of phosphatidylinositol. Because of GPI-dependent membrane anchoring, GPI-APs have some unique characteristics. The most prominent feature of GPI-APs is their association with membrane microdomains or membrane rafts. In the polarized cells such as epithelial cells, many GPI-APs are exclusively expressed in the apical surfaces, whereas some GPI-APs are preferentially expressed in the basolateral surfaces. Several GPI-APs act as transcytotic transporters carrying their ligands from one compartment to another. Some GPI-APs are shed from the membrane after cleavage within the GPI by a GPI-specific phospholipase or a glycosidase. In this review, I will summarize the current understanding of GPI-AP biosynthesis in mammalian cells and discuss examples of GPI-dependent functions of mammalian GPI-APs.

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Human SND2 mediates ER targeting of GPI‐anchored proteins with low hydrophobic GPI attachment signals

et al. 2021

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Over 100 glycosylphosphatidylinositol‐anchored proteins (GPI‐APs) are encoded in the mammalian genome. It is not well understood how these proteins are targeted and translocated to the endoplasmic reticulum (ER). Here, we reveal that many GPI‐APs, such as CD59, CD55, and CD109, utilize human SND2 (hSND2)‐dependent ER targeting machinery. We also found that signal recognition particle receptors seem to cooperate with hSND2 to target GPI‐APs to the ER. Both the N‐terminal signal sequence and C‐terminal GPI attachment signal of GPI‐APs contribute to ER targeting via the hSND2‐dependent pathway. Particularly, the hydrophobicity of the C‐terminal GPI attachment signal acts as the determinant of hSND2 dependency. Our results explain the route and mechanism of the ER targeting of GPI‐APs in mammalian cells.

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N-Glycan–dependent protein folding and endoplasmic reticulum retention regulate GPI-anchor processing

Cited by 60 publications

References 55 publications

Calnexin mediates the maturation of GPI-anchors through ER retention

Calnexin mediates the maturation of GPI-anchors through ER retention

Biosynthesis and biology of mammalian GPI-anchored proteins

Human SND2 mediates ER targeting of GPI‐anchored proteins with low hydrophobic GPI attachment signals

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