Cryo–electron microscopy structures of human oligosaccharyltransferase complexes OST-A and OST-B

• DOI: 10.1126/science.aaz3505
• Publication Date: 2019-12-13T00:05:40Z
• Authors: Ana S. Ramírez; Julia Kowal; Kaspar P. Locher
• Keywords: 0301 basic medicine; Protein Subunits; 03 medical and health sciences; Hexosyltransferases; Protein Conformation; Cryoelectron Microscopy; Humans; Membrane Proteins

A division of labor for glycosylation

Glycosylation is a ubiquitous modification of eukaryotic secreted proteins. Asparagine-linked chains of sugars are appended to many substrates as they are translocated into the endoplasmic reticulum. Ramírez et al. solved cryo–electron microscopy structures of two human oligosaccharyltransferase complexes, OST-A and OST-B. The catalytic subunits bind partner proteins that direct glycosylation of specific substrates either cotranslationally (OST-A) or on fully folded proteins (OST-B). High-resolution views of the active site and bound substrates in one of the complexes reveal important features of the human enzymes.

Science , this issue p. 1372