Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein folding mediated by the molecular chaperone GroEL occurs by its binding to non-native polypeptide substrates and is driven by ATP hydrolysis. Both of these processes are influenced by the reversible association of the co-protein, GroES (refs 2-4). GroEL and other chaperonin 60 molecules are large, cylindrical oligomers consisting of two stacked heptameric rings of subunits; each ring forms a cage-like structure thought to bind polypeptides in a central cavity. Chaperonins play a passive role in folding by binding or sequestering folding proteins to prevent their aggregation, but they may also actively unfold substrate proteins trapped in misfolded forms, enabling them to assume productive folding conformations. Biochemical studies show that GroES improves the efficiency of GroEL function, but the structural basis for this is unknown. Here we report the first direct visualization, by cryo-electron microscopy, of a non-native protein substrate (malate dehydrogenase) bound to the mobile, outer domains at one end of GroEL. Addition of GroES to GroEL in the presence of ATP causes a dramatic hinge opening of about 60 degrees. GroES binds to the equivalent surface of the GroEL outer domains, but on the opposite end of the GroEL oligomer to the protein substrate.
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PMID:Location of a folding protein and shape changes in GroEL-GroES complexes imaged by cryo-electron microscopy. 791 27

The safe performance of a right hepatic lobectomy requires adequate exposure of the hepatic veins and of the suprahepatic vena cava. An extended subcostal or midline incision is commonly used to provide exposure for this operation. The technique for an extended subcostal incision that uses the natural hinge mechanism of the rib cage to provide exposure to the right upper quadrant is described. This approach provides adequate exposure during a difficult hepatectomy, avoiding the need for a thoracotomy or sternotomy.
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PMID:Extended subcostal hinge incision for right hepatic lobectomy. 1043 90

Activation of cytotoxic T cells without MHC restriction was attempted by expressing single-chain antibodies (scFv) against CD3 on the surface of tumor cells. A chimeric protein consisting of a scFv of mAb 145.2C11, the hinge-CH2-CH3 region of human IgG1, and the transmembrane and cytosolic domains of murine CD80 formed disulfide-linked dimers on the plasma membrane of cells and specifically bound lymphocytes. Anti-CD3 scFv dimers expressed on the cell surface induced CD25 (IL-2 receptor alpha-chain) expression and proliferation of splenocytes. CT26 tumor cells engineered to express surface scFv dimers (CT26/2C11) also induced potent lymphocyte cytotoxicity with or without addition of exogenous IL-2. Splenocytes activated by CT26/2C11 cells also killed wild-type CT26 cells, indicating that activated splenocytes could kill bystander tumor cells. Immunization of BALB/c mice with irradiated CT26/2C11 cells did not protect against a lethal challenge of CT26 cells, suggesting that systemic immunity was not induced. However, the growth of CT26 tumors containing 50% CT26/2C11 cells was significantly retarded compared with CT26 tumors, whereas CT26/2C11 tumors did not grow in syngeneic mice. These results suggest that expression of anti-CD3 scFv dimers on tumors may form the basis for a novel therapeutic strategy for tumors that exhibit defects in antigen processing or presentation. Gene Therapy (2000) 7, 339-347.
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PMID:Activation of lymphocytes by anti-CD3 single-chain antibody dimers expressed on the plasma membrane of tumor cells. 1069 15

The Dna J homologue, auxilin, acts as a co-chaperone for Hsc70 in the uncoating of clathrin-coated vesicles during endocytosis. Biochemical studies have aided understanding of the uncoating mechanism but until now there was no structural information on how auxilin interacts with the clathrin cage. Here we have determined the three-dimensional structure of a complex of auxilin with clathrin cages by cryo-electron microscopy and single particle analysis. We show that auxilin forms a discrete shell of density on the inside of the clathrin cage. Peptide competition assays confirm that a candidate clathrin box motif in auxilin, LLGLE, can bind to a clathrin construct containing the beta-propeller domain and also displace the well-characterised LLNLD clathrin box motif derived from the beta-adaptin hinge region. The means by which auxilin could both aid clathrin coat assembly and displace clathrin from AP2 during uncoating is discussed.
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PMID:Location of auxilin within a clathrin cage. 1475 58

Thirty percent of the 189 tumors studied to date express DNA polymerase beta variants. One of these variants was identified in a prostate carcinoma and is altered from isoleucine to methionine at position 260, within the hydrophobic hinge region of the protein. Another variant was identified in a colon carcinoma and is altered at position 289 from lysine to methionine, within helix N of the protein. We have shown that the types of mutations induced by these cancer-associated variants are different from those induced by the wild-type enzyme. In this study, we show that expression of the I260M and K289M cancer-associated variants in mouse C127 cells results in a transformed phenotype in the great majority of cell clones tested, as assessed by focus formation and anchorage-independent growth. Strikingly, cellular transformation occurs after a variable number of passages in culture but, once established, does not require continuous expression of the polymerase beta variant proteins, implying that it has a mutational basis. Because DNA polymerase beta functions in base excision repair, our results suggest that mutations that arise during this process can lead to the onset or progression of cancer.
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PMID:Expression of DNA polymerase {beta} cancer-associated variants in mouse cells results in cellular transformation. 1617 90

Studies show that 30% of 189 tumors sequenced to date express variants of the polymerase beta (pol beta) protein that are not present in normal tissue. This raises the possibility that variants of pol beta might be linked to the etiology of cancer. Here, we characterize the I260M prostate-cancer-associated variant of pol beta. Ile260 is a key residue of the hydrophobic hinge that is important for the closing of the polymerase. In this study, we demonstrate that the I260M variant is a sequence context-dependent mutator polymerase. Specifically, I260M is a mutator for misalignment-mediated errors in dipyrimidine sequences. I260M is also a low-fidelity polymerase with regard to the induction of transversions within specific sequence contexts. Our results suggest that the hinge influences the geometry of the DNA within the polymerase active site that is important for accurate DNA synthesis. Importantly, characterization of the I260M variant shows that it has a functional phenotype that could be linked to the etiology or malignant progression of human cancer.
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PMID:Prostate-cancer-associated I260M variant of DNA polymerase beta is a sequence-specific mutator. 1631 69

Plants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus. Mutations of aromatic cage residues that recognize methyl K9 of histone H3 abolished their punctuated distribution and localization to chromocenters. Sl LHP1-GFP plants displayed cell type-dependent subnuclear localization. The diverse localization pattern of tomato LHP1 did not require the chromo shadow domain (CSD), whereas the chromodomain alone was insufficient for localization to chromocenters; a nucleolar localization signal was identified within the hinge region. Fluorescence recovery after photobleaching showed that Sl LHP1 is a highly mobile protein whose localization and retention are controlled by distinct domains; retention at the nucleolus and chromocenters is conferred by the CSD. Our results imply that LHP1 recruitment to chromatin is mediated, at least in part, through interaction with methyl K9 and that LHP1 controls different nuclear processes via transient binding to its nuclear sites.
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PMID:Different domains control the localization and mobility of LIKE HETEROCHROMATIN PROTEIN1 in Arabidopsis nuclei. 1636 94

COPII-coated vesicles export newly synthesized proteins from the endoplasmic reticulum. The COPII coat consists of the Sec23/24-Sar1 complex that selects cargo and the Sec13/31 assembly unit that can polymerize into an octahedral cage and deform the membrane into a bud. Crystallographic analysis of the assembly unit reveals a 28 nm long rod comprising a central alpha-solenoid dimer capped by two beta-propeller domains at each end. We construct a molecular model of the COPII cage by fitting Sec13/31 crystal structures into a recently determined electron microscopy density map. The vertex geometry involves four copies of the Sec31 beta-propeller that converge through their axial ends; there is no interdigitation of assembly units of the kind seen in clathrin cages. We also propose that the assembly unit has a central hinge-an arrangement of interlocked alpha-solenoids-about which it can bend to adapt to cages of variable curvature.
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PMID:Structure and organization of coat proteins in the COPII cage. 1760 13

The human p100 protein is a vital transcription regulator that increases gene transcription by forming a physical bridge between promoter-specific activators and the basal transcription machinery. Here we demonstrate that the tudor and SN (TSN) domain of p100 interacts with U small nuclear ribonucleoprotein (snRNP) complexes, suggesting a role for p100 in the processing of precursor messenger RNA. We determined the crystal structure of the p100 TSN domain to delineate the molecular basis of p100's proposed functions. The interdigitated structure resembles a hook, with a hinge controlling the movement and orientation of the hook. Our studies suggest that a conserved aromatic cage hooks methyl groups of snRNPs and anchors p100 to the spliceosome. These structural insights partly explain the distinct roles of p100 in transcription and splicing.
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PMID:The multifunctional human p100 protein 'hooks' methylated ligands. 1763 23

Using cryo-electron microscopy, we have solved the structure of an icosidodecahedral COPII coat involved in cargo export from the endoplasmic reticulum (ER) coassembled from purified cargo adaptor Sec23-24 and Sec13-31 lattice-forming complexes. The coat structure shows a tetrameric assembly of the Sec23-24 adaptor layer that is well positioned beneath the vertices and edges of the Sec13-31 lattice. Fitting the known crystal structures of the COPII proteins into the density map reveals a flexible hinge region stemming from interactions between WD40 beta-propeller domains present in Sec13 and Sec31 at the vertices. The structure shows that the hinge region can direct geometric cage expansion to accommodate a wide range of bulky cargo, including procollagen and chylomicrons, that is sensitive to adaptor function in inherited disease. The COPII coat structure leads us to propose a mechanism by which cargo drives cage assembly and membrane curvature for budding from the ER.
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PMID:Structural basis for cargo regulation of COPII coat assembly. 1869 60


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