Yeast Wbp1p and Swp1p form a protein complex essential for oligosaccharyl transferase activity.

AUTOR(ES)

te Heesen, S

RESUMO

Asparagine-linked N-glycosylation is an essential protein modification occurring in all eukaryotic cells. The central step is the co-translational transfer of the core oligosaccharide assembled on the lipid carrier dolichol phosphate to selected Asn-X-Ser/Thr residues of nascent polypeptide chains in the endoplasmic reticulum. This reaction is catalyzed by the enzyme N-oligosaccharyl transferase. In yeast, Wbp1p is an essential component of this enzyme. Using a high copy number suppression approach, the SWP1 gene was isolated as an allele specific suppressor of a wbp1 mutation. Swp1p is a 30 kDa type I transmembrane protein and essential for cell viability. Similar to Wbp1p, depletion of Swp1p results in reduced N-oligosaccharyl transferase activity in vivo and in vitro. Wbp1p and Swp1p can be chemically cross-linked, suggesting that both proteins are essential constituents of the N-oligosaccharyl transferase complex.

Documentos Relacionados

• The yeast WBP1 is essential for oligosaccharyl transferase activity in vivo and in vitro.
• STT3, a highly conserved protein required for yeast oligosaccharyl transferase activity in vivo.
• Identification of a ribosomal protein essential for peptidyl transferase activity.
• Rhizobium meliloti NodP and NodQ form a multifunctional sulfate-activating complex requiring GTP for activity.
• A 105-kDa protein is required for yeast mitochondrial RNase P activity.