Term
| Actin Filaments and Microtubules |
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Definition
distinct gene products BUT markedly similar mechanisms of function
- regulated assembly from a large number of locations
- highly dynamic
- polarized
- tracks for myosins/kinesins and dyneins |
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Term
| Microtubule Site: Cytoplasm |
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Definition
- positioning of organelles
- Trafficking of vesicles |
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Term
| Microtubule Site: Motile Cilia |
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Definition
9+2 configuration
- airway epithelial cells
- apical (lumenal) membrane
- particle clearance |
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Term
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Definition
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Term
| Microtubule Site: Primary Cilia |
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Definition
9+0 configuration
- epithelial cells
- immotile
- sensory organelle |
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Term
| Microtubule Site: Neuronal Axons |
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Definition
- anterograde transport
- retrograde transport |
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Term
| Microtubule Site: Mitotic Spindles |
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Definition
| - segregation of chromosomes |
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Term
| Organization of the Microtubule Wall |
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Definition
- tubulin heterodimers stack to form protofilaments
- MT wall (25 nm) has 13 tubulin protofilaments
- Lateral interactions stabilize MT wall
- there is a 3-subunit rise in a full turn
- a-B mismatch produces a seam
- microtubules have POLARITY |
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Term
| Microtubule Organization Center (MTOC) |
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Definition
| sites to nucleate MT assembly |
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Term
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Definition
- centrioles (length: 0.5 micron,diameter: 0.2 microns)
- pericentriolar material
- gamma-tubulin ring complex |
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Term
| Gamma-Tubulin Ring Complex |
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Definition
- binds and orients gamma-tubulin
- binds and stabilizes the MT (-)end |
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Term
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Definition
individual MTs undergo constant growth and shrinkage
- growth rates: ~1 micron/min
- shrinkage rates: ~7 microns/min |
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Term
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Definition
growing MT: blunt end
- rate of GTP-B-tubulin addition > rate of GTP hydrolysis |
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Term
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Definition
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Term
| Microtubule Associated Proteins (MAP) |
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Definition
specific proteins co-purify with tubulin (brain homogenates)
- co-precipitated proteins "decorate" MTs in vitro
- moderating MT dynamics |
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Term
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Definition
Tau-family of proteins
- bind to lateral aspects of MT (+ charged 18 aa repeats)
- stabilizes MT against catastrophe
- moderate MT spacing |
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Term
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Definition
neuronal proteins found within the axons
- impact MT spacing
- axon-like projections in non-neuronal cell line following tau or MAP2 transfection |
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Term
| +-Tip Binding Proteins - EB1 |
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Definition
promoting GROWTH AND STABILITY (plus end tracking proteins)
- can enhance polymerization
- can inhibit catastrophe
- can help capture appropriate targets |
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Term
| +-Tip Binding Proteins - Kinesin-13 and Stathmin |
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Definition
promoting CATASTROPHE (plus end tracking proteins)
- can induce severing of the + end
- shortens MT length
- removes GTP-Tubulin cap |
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Term
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Definition
- binds + end of MT
- severs end dimers
- ATP-dependent |
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Term
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Definition
- binds two dimer pairs
- bends pairs into GDP configuration
- regulated by phosphorylation |
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Term
| Lysine Acetylation/Detyrosylation |
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Definition
Post-Translational Modification of Microtuble
- stabilizes MT/kinesin-1 |
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Term
| Polyglutamylation/polyglycylation |
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Definition
Post-Translational Modification of Microtubule
- stabilizes MT |
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Term
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Definition
depolymerize MTs
- bind to soluble heterodimers
- prevents assembly
- shift equilibrium |
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Term
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Definition
stabilize MTs
- bind to assembled MT (along inner MT surface)
- shift equilibrium |
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Term
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Definition
- found in the meadow saffron
- an early treatment for gout
- King Henry VIII was treated for gout
- likely inhibited the inflammatory response by white blood cell in gout patients |
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Term
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Definition
| Structural Support and Organization of Higher Eukaryotes |
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Term
| Distinguishing Characteristics of IF vs. MT/MF |
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Definition
- biochemically heterogeneous subunits
- great TENSILE strength
- NO intrinsic polarity
- NO nucleotide binding
- NO known IF-Motor Proteins
- much more stable
- not found in ALL eukaryotes |
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Term
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Definition
| Amount of 'pull' on a filament |
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Term
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Definition
| resulting deformation from stress |
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Term
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Definition
| nuclear localization signal |
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Term
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Definition
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Term
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Definition
- obligate heterodimers: one acidic and one basic keratin per dimer
- keratins are linked to desmosomes vis desmoplakin
- mechanical forces of the skin are borne by keratins and transferred to the underlying dermal layer |
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Term
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Definition
- desmin in myocytes (striated muscle)
- tethers to Z-discs, in register, to the surrounding sarcolemma |
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Term
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Definition
three related subunits:
- NF-L (light)
- NF-M (medium)
- NF-H (heavy)
- variance is due to differences in the C terminal domain
- form heterodimers
- present in the axons of neurons |
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Term
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Definition
- diminished axonal diameters
- slower rates of AP conduction
- mice are viable
**neurofilaments impact the diameters of axons |
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Term
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Definition
Three genes in humans
- one gene for A and C type (alternative spliceoforms)
- expression is developmentally regulated
- Two genes for B type
- the primordial lamin protein
- constituitively expressed in all lamin-containing cells
- isoprenylated (localize to the INM)
- bind to INM proteins (e.g. LBR, emerin, LAP2)
- tether chromosomal DNA to the INM
- phosphorylation (CDK1) results in disassembly |
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Term
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Definition
| genetic diseases of intermediate filaments |
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Term
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Definition
| crosslinker between intermediate filaments and MTs/MFs |
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