PowerPoint Presentation - Molecular Cell Biology
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Molecular Cell Biology
Myosin
Cooper
Diagram of a Sarcomere
Sliding Filament Model:
Length-Tension Relationship
Tension
(Force
produced
by Muscle
Contraction)
Physiological Part
of the Curve
Length (of the Sarcomere)
Myosin Moving on Actin Filament in Muscle
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Video decompressor
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ActoMyosin Cycle:
ATP Hydrolysis &
Movement
Structure of Myosin Head & Neck
Evidence for Twisting Head Model:
Myosin Lever Arm Orientations
Thin Filament Proteins Drawn to Scale
Troponin
Actin
Tropomyosin
Simple Steric Blocking Model
Ac
Tm
Ac
Myosin
Off
Tm
Ac
Ac
On
Myosin
Familial Hypertrophic Cardiomyopathy
Inherited human disease
• Heart dysfunction and sudden death
Autosomal dominant
Myosin heavy chain gene first
Other sarcomere components
Subtle mutations
• Mild effects on Biochemical Function
Myosin: Definitions
Biochemical: Actin-activated ATPase
Mechanical: Moves along actin filament
Structural: Conserved motor domain, with
binding sites for actin and ATP
Structural
Regions of
Myosins
Phylogenetic
Tree of
Myosins
Myosin II: Contraction
Bipolar Filaments
Stress Fibers
Contractile Ring of Cytokinesis
Tail Contraction in Cell Migration
• Toothpaste Tube Model
Epithelial Cells
• Folding a Layer in Development
• Apoptosis - Extruding a Cell
Myosin-V: Hand-over-hand Processivity
Myosin-V: Molecular Movement
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Atomic Force Microscopy
Atomic Force Microscopy
Tapping Mode
Myosin V Auto-Inhibition
Myosin V in
Budding Yeast
Tracks of Actin Filaments...
•Anchored via Barbed Ends
•At Specific Locations on the Plasma Membrane (1)
•Filaments Bundled (2)
Myosin V in
Budding Yeast
Cargos for the Myosin...
•Secretory Vesicles for Polarized Growth (3)
•Distal Plus Ends of Mts, to Position the Mitotic Spindle (4)
•mRNA to Specify Daughter-Cell Property (5)
•Inheritance / Segregation of Organelles, e.g. Vacuole/Lysosome (6)
Myosin VI
Moves Backward - Toward Pointed End
Motor domain has insertion sequence in position
similar to an insertion in Ncd, the backwards kinesin
Associated w/ Unusual Actin Filament Structures
during Spermatogenesis in Drosophila and C.
elegans
Hair Cell Sound Adap tation and Myo1c
Tip Links by Scanning EM: Effect of Sound
Control
After Intense Sound
External Swf Files
Channel Gating
Positive adaptation
Negative adaptation
Myosin Isoform Localization
Ic
VI
VIIa
Myo1c Localization
by ImmunoEM
NMB-ADP Analogue Strategy
for Inhibiting an ATPase
Electrophysiology Results
Model
Wild-type
Mutant
End