例如:"lncRNA", "apoptosis", "WRKY"

Glucosidase II and N-glycan mannose content regulate the half-lives of monoglucosylated species in vivo.

Mol. Biol. Cell. 2011 Jun 1;22(11):1810-23. Epub 2011 Apr 06
Ivan D Stigliano 1 , Solana G Alculumbre , Carlos A Labriola , Armando J Parodi , Cecilia D'Alessio
Ivan D Stigliano 1 , Solana G Alculumbre , Carlos A Labriola , Armando J Parodi , Cecilia D'Alessio

[No authors listed]

Author information
  • 1 Laboratory of Glycobiology, Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, C1405BWE, Buenos Aires, Argentina.

摘要


Glucosidase II (GII) sequentially removes the two innermost glucose residues from the glycan (Glc(3)Man(9)GlcNAc(2)) transferred to proteins. GII also participates in cycles involving the lectin/chaperones calnexin (CNX) and calreticulin (CRT) as it removes the single glucose unit added to folding intermediates and misfolded glycoproteins by the UDP-Glc:glycoprotein glucosyltransferase (UGGT). GII is a heterodimer in which the α subunit (GIIα) bears the active site, and the β subunit (GIIβ) modulates GIIα activity through its C-terminal mannose 6-phosphate receptor homologous (MRH) domain. Here we report that, as already described in cell-free assays, in live Schizosaccharomyces pombe cells a decrease in the number of mannoses in the glycan results in decreased GII activity. Contrary to previously reported cell-free experiments, however, no such effect was observed in vivo for UGGT. We propose that endoplasmic reticulum α-mannosidase-mediated N-glycan demannosylation of misfolded/slow-folding glycoproteins may favor their interaction with the lectin/chaperone CNX present in S. pombe by prolonging the half-lives of the monoglucosylated glycans (S. pombe lacks CRT). Moreover, we show that even N-glycans bearing five mannoses may interact in vivo with the GIIβ MRH domain and that the N-terminal GIIβ G2B domain is involved in the GIIα-GIIβ interaction. Finally, we report that protists that transfer glycans with low mannose content to proteins have nevertheless conserved the possibility of displaying relatively long-lived monoglucosylated glycans by expressing GIIβ MRH domains with a higher specificity for glycans with high mannose content.

基因