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

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Proteins entering the endoplasmic reticulum are often N-glycosylated for proper folding and stability.
• N-glycosylation is a crucial co- and posttranslational modification in the secretory pathway.

Purpose of the Study:

• To investigate the role of the signal recognition particle receptor (SR) alpha subunit in N-glycosylation.
• To identify mechanisms by which SR-alpha influences the N-glycosylation machinery.

Main Methods:

• Utilized high-throughput screening to identify guanine analog chemical probes targeting SR-alpha.
• Introduced mutations in the guanosine triphosphate binding site of SR-alpha.
• Assessed protein association with the oligosaccharyltransferase complex.

Main Results:

• Chemical probes and mutations targeting SR-alpha's GTP binding site led to N-glycosylation deficiency.
• These modifications did not disrupt SR-alpha's interaction with SR-beta.
• However, they reduced SR-alpha's association with the oligosaccharyltransferase complex.

Conclusions:

• The SR-alpha subunit plays a critical role in coordinating translation and N-glycosylation in the endoplasmic reticulum.
• SR-alpha's function extends beyond signal recognition, influencing the N-glycosylation machinery.
• This highlights a novel regulatory mechanism linking protein translocation and modification.