4m91
From Proteopedia
crystal structure of hN33/Tusc3-peptide 1
Structural highlights
Disease[TUSC3_HUMAN] Autosomal recessive nonsyndromic intellectual deficit. The disease is caused by mutations affecting the gene represented in this entry. [CRBN_HUMAN] Autosomal recessive nonsyndromic intellectual deficit;Distal monosomy 3p. The disease is caused by mutations affecting the gene represented in this entry. Function[TUSC3_HUMAN] Magnesium transporter. May be involved in N-glycosylation through its association with N-oligosaccharyl transferase.[1] [CRBN_HUMAN] Component of some DCX (DDB1-CUL4-X-box) E3 protein ligase complex, a complex that mediates the ubiquitination and subsequent proteasomal degradation of target proteins and is required for limb outgrowth and expression of the fibroblast growth factor FGF8. In the complex, may act as a substrate receptor. Regulates the assembly and neuronal surface expression of large-conductance calcium-activated potassium channels in brain regions involved in memory and learning via its interaction with KCNT1.[2] [3] Publication Abstract from PubMedN-linked glycosylation of proteins in the endoplasmic reticulum (ER) is essential in eukaryotes and catalyzed by oligosaccharyl transferase (OST). Human OST is a hetero-oligomer of seven subunits. The subunit N33/Tusc3 is a tumor suppressor candidate, and defects in the subunit N33/Tusc3 are linked with nonsyndromic mental retardation. Here, we show that N33/Tusc3 possesses a membrane-anchored N-terminal thioredoxin domain located in the ER lumen that may form transient mixed disulfide complexes with OST substrates. X-ray structures of complexes between N33/Tusc3 and two different peptides as model substrates reveal a defined peptide-binding groove adjacent to the active site that can accommodate peptides in opposite orientations. Structural and biochemical data show that N33/Tusc3 prefers peptides bearing a hydrophobic residue two residues away from the cysteine forming the mixed disulfide with N33/Tusc3. Our results support a model in which N33/Tusc3 increases glycosylation efficiency for a subset of human glycoproteins by slowing glycoprotein folding. Structural basis of substrate specificity of human oligosaccharyl transferase subunit n33/tusc3 and its role in regulating protein N-glycosylation.,Mohorko E, Owen RL, Malojcic G, Brozzo MS, Aebi M, Glockshuber R Structure. 2014 Apr 8;22(4):590-601. doi: 10.1016/j.str.2014.02.013. Epub 2014, Mar 27. PMID:24685145[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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