Structure of human glycosylphosphatidylinositol transamidase.
Nat Struct Mol Biol
; 29(3): 203-209, 2022 03.
Article
in En
| MEDLINE
| ID: mdl-35165458
ABSTRACT
Glycosylphosphatidylinositol (GPI) molecules are complex glycophospholipids and serve as membrane anchors for tethering many proteins to the cell surface. Attaching GPI to the protein in the endoplasmic reticulum (ER) is catalyzed by the transmembrane GPI transamidase (GPIT) complex, which is essential for maturation of the GPI-anchored proteins. The GPIT complex is known to be composed of five subunits PIGK, PIGU, PIGT, PIGS and GPAA1. Here, we determined the structure of the human GPIT complex at a resolution of 3.1 Å using single-particle cryo-EM, elucidating its overall assembly. The PIGK subunit functions as the catalytic component, in which we identified a C206-H164-N58 triad that is critical for the transamination reaction. Transmembrane helices constitute a widely opened cleft, which is located underneath PIGK, serving as a GPI substrate-binding site. The ubiquitin E3 ligase RNF121 is visualized at the back of the complex and probably serves as a quality control factor for the GPIT complex.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Acyltransferases
/
Glycosylphosphatidylinositols
Type of study:
Prognostic_studies
Limits:
Humans
Language:
En
Journal:
Nat Struct Mol Biol
Journal subject:
BIOLOGIA MOLECULAR
Year:
2022
Document type:
Article
Affiliation country: