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Articles 1 - 4 of 4

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Disulfide Bond Formation Involves A Quinhydrone-Type Charge–Transfer Complex, James Regeimbal, Stefan Gleiter, Bernard L. Trumpower, Chang-Ang Yu Nov 2003

Disulfide Bond Formation Involves A Quinhydrone-Type Charge–Transfer Complex, James Regeimbal, Stefan Gleiter, Bernard L. Trumpower, Chang-Ang Yu

Open Dartmouth: Faculty Open Access Scholarship

The chemistry of disulfide exchange in biological systems is well studied. However, the detailed mechanism of how oxidizing equivalents are derived to form disulfide bonds in proteins is not clear. In prokaryotic organisms, it is known that DsbB delivers oxidizing equivalents through DsbA to secreted proteins. DsbB becomes reoxidized by reducing quinones that are part of the membrane-bound electron-transfer chains. It is this quinone reductase activity that links disulfide bond formation to the electron transport system. We show here that purified DsbB contains the spectral signal of a quinhydrone, a charge-transfer complex consisting of a hydroquinone and a quinone in ...


A Role For Yip1p In Copii Vesicle Biogenesis, Matthew Heidtman, Catherine Z. Chen, Ruth N. Collins, Charles Barlowe Oct 2003

A Role For Yip1p In Copii Vesicle Biogenesis, Matthew Heidtman, Catherine Z. Chen, Ruth N. Collins, Charles Barlowe

Open Dartmouth: Faculty Open Access Scholarship

Yeast Ypt1p-interacting protein (Yip1p) belongs to a conserved family of transmembrane proteins that interact with Rab GTPases. We encountered Yip1p as a constituent of ER-derived transport vesicles, leading us to hypothesize a direct role for this protein in transport through the early secretory pathway. Using a cell-free assay that recapitulates protein transport from the ER to the Golgi complex, we find that affinity-purified antibodies directed against the hydrophilic amino terminus of Yip1p potently inhibit transport. Surprisingly, inhibition is specific to the COPII-dependent budding stage. In support of this in vitro observation, strains bearing the temperature-sensitive yip1-4 allele accumulate ER membranes ...


Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor Mar 2003

Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor

Open Dartmouth: Faculty Open Access Scholarship

Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living alpha-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established ...


Rpb4p, A Subunit Of Rna Polymerase Ii, Mediates Mrna Export During Stress, Marganit Farago, Tal Nahari, Christopher Hammel, Charles N. Cole, Mordechai Choder Feb 2003

Rpb4p, A Subunit Of Rna Polymerase Ii, Mediates Mrna Export During Stress, Marganit Farago, Tal Nahari, Christopher Hammel, Charles N. Cole, Mordechai Choder

Open Dartmouth: Faculty Open Access Scholarship

Changes in gene expression represent a major mechanism by which cells respond to stress. We and other investigators have previously shown that the yeast RNA polymerase II subunit Rpb4p is required for transcription under various stress conditions, but not under optimal growth conditions. Here we show that, in addition to its role in transcription, Rpb4p is also required for mRNA export, but only when cells are exposed to stress conditions. The roles of Rpb4p in transcription and in mRNA export can be uncoupled genetically by specific mutations in Rpb4p. Both functions of Rpb4p are required to maintain cell viability during ...