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Medical Biochemistry Commons

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Full-Text Articles in Medical Biochemistry

Analysis Of Mitotic Microtubule-Associated Proteins Using Mass Spectrometry Identifies Astrin, A Spindle-Associated Protein, Gary J. Mack, Duane A. Compton Dec 2001

Analysis Of Mitotic Microtubule-Associated Proteins Using Mass Spectrometry Identifies Astrin, A Spindle-Associated Protein, Gary J. Mack, Duane A. Compton

Dartmouth Scholarship

We purified microtubules from a mammalian mitotic extract and obtained an amino acid sequence from each microtubule-associated protein by using mass spectrometry. Most of these proteins are known spindle-associated components with essential functional roles in spindle organization. We generated antibodies against a protein identified in this collection and refer to it as astrin because of its association with astral microtubule arrays assembled in vitro. Astrin is approximately 134 kDa, and except for a large predicted coiled-coil domain in its C-terminal region it lacks any known functional motifs. Astrin associates with spindle microtubules as early as prophase where it concentrates at …


Distinct Retrieval And Retention Mechanisms Are Required For The Quality Control Of Endoplasmic Reticulum Protein Folding, Shilpa Vashist, Woong Kim, William J. Belden, Eric D. Spear, Charles Barlowe, Davis T.W. Ng Oct 2001

Distinct Retrieval And Retention Mechanisms Are Required For The Quality Control Of Endoplasmic Reticulum Protein Folding, Shilpa Vashist, Woong Kim, William J. Belden, Eric D. Spear, Charles Barlowe, Davis T.W. Ng

Dartmouth Scholarship

Proteins destined for the secretory pathway must first fold and assemble in the lumen of endoplasmic reticulum (ER). The pathway maintains a quality control mechanism to assure that aberrantly processed proteins are not delivered to their sites of function. As part of this mechanism, misfolded proteins are returned to the cytosol via the ER protein translocation pore where they are ubiquitinated and degraded by the 26S proteasome. Previously, little was known regarding the recognition and targeting of proteins before degradation. By tracking the fate of several mutant proteins subject to quality control, we demonstrate the existence of two distinct sorting …


The Chromokinesin Kid Is Necessary For Chromosome Arm Orientation And Oscillation, But Not Congression, On Mitotic Spindles, Aime A. Levesque, Duane A. Compton Sep 2001

The Chromokinesin Kid Is Necessary For Chromosome Arm Orientation And Oscillation, But Not Congression, On Mitotic Spindles, Aime A. Levesque, Duane A. Compton

Dartmouth Scholarship

Chromokinesins have been postulated to provide the polar ejection force needed for chromosome congression during mitosis. We have evaluated that possibility by monitoring chromosome movement in vertebrate-cultured cells using time-lapse differential interference contrast microscopy after microinjection with antibodies specific for the chromokinesin Kid. 17.5% of cells injected with Kid-specific antibodies have one or more chromosomes that remain closely opposed to a spindle pole and fail to enter anaphase. In contrast, 82.5% of injected cells align chromosomes in metaphase, progress to anaphase, and display chromosome velocities not significantly different from control cells. However, injected cells lack chromosome oscillations, and chromosome orientation …


Circadian Clock-Specific Roles For The Light Response Protein White Collar-2, Michael A. Collett, Jay C. Dunlap, Jennifer J. Loros Apr 2001

Circadian Clock-Specific Roles For The Light Response Protein White Collar-2, Michael A. Collett, Jay C. Dunlap, Jennifer J. Loros

Dartmouth Scholarship

To understand the role of white collar-2 in theNeurospora circadian clock, we examined alleles ofwc-2 thought to encode partially functional proteins. We found that wc-2 allele ER24 contained a conservative mutation in the zinc finger. This mutation results in reduced levels of circadian rhythm-critical clock gene products, frq mRNA and FRQ protein, and in a lengthened period of the circadian clock. In addition, this mutation altered a second canonical property of the clock, temperature compensation: as temperature increased, period length decreased substantially. This temperature compensation defect correlated with a temperature-dependent increase in overall FRQ protein levels, with the …