Signal recognition particle receptor-β (SR-β) coordinates cotranslational N-glycosylation

Proteins destined for the secretory compartment of the cell are cotranslationally translocated into the endoplasmic reticulum. The majority of these proteins are N-glycosylated, a co- and posttranslational modification that ensures proper protein folding, stability, solubility, and cellular localization. Here, we show that the [Formula: see text] subunit of the signal recognition particle receptor (SR) is required for assembly of the N-glycosylation–competent translocon. We report that guanine analog chemical probes identified by high-throughput screening or mutation of the SR- [Formula: see text] guanosine triphosphate binding site cause an N-glycosylation–deficient phenotype. Neither method alters the association of SR- [Formula: see text] with SR- [Formula: see text] , but both approaches reduce the association of SR- [Formula: see text] with the oligosaccharyltransferase complex. These experiments demonstrate that SR- [Formula: see text] has a previously unrecognized function coordinating endoplasmic reticulum translation with N-glycosylation.