cells. They also form
stress fibers that give shape to the
cell. Theyare highly dynamic forming networks that
serve as the basis for cellular motility.
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Lectures 21 and 22: The Cytoskeleton: Microfilaments Essential Cell
Содержание
- 1. Lectures 21 and 22: The Cytoskeleton: Microfilaments Essential Cell
- 2. The Cytoskeleton Includes Dynamic NetworksOf Microfilaments And Microfilaments
- 3. Microfilaments composed of actin are oftenfound at
- 4. Microfilaments Consist Of A Double HelixOf Actin Monomers Bound To Each Other
- 5. Microfilaments (MFs) consist of a double helixOf
- 6. Actin Polymerization Can Occur In Vitro. No Other Proteins Are Required.
- 7. Microfilaments like microtubules have plus and minus
- 8. Animation: Regulation of Actin Polymerization and
- 9. 3-D Microfilament Networks Are The Basis Of
- 10. Microfilaments Interact With accessory proteins (actin binding
- 11. Microfilaments Form Bundles using the crosslinking proteins
- 12. Microvilli Contain A Microfilament Bundle
- 13. Microfilamentelongation in vivois aided by theaccessory proteinsprofilin
- 14. Animation of Actin Polymerization using Formin
- 15. In cells, the ends of microfilaments are
- 16. ARPs allow binding of minus ends to
- 17. Dynamics of Actin Networks in a slime mold.
- 18. Micro-FilamentNetworks Are TheBasis OfAmoeboidMovementTHE LEADING EDGETHE LEADING EDGE
- 19. Steps In The Cycle Of Amoeboid MovementExtension
- 20. Microfilament Networks Are Dynamic At The Leading Edge
- 21. Animation of ARP 2/3 induced branching of microfilaments as facilitated by WASP proteins
- 22. Cell Signaling ControlsThe Actin CytoskeletonForminActin polymerizationand branching
- 23. Micro-FilamentNetworks Are theBasis ofAmeoboidMovementTHE LEADING EDGE
- 24. Steps In The Cycle Of Amoeboid MovementExtension
- 25. Focal adhesions use hundreds of transmembrane proteins
- 26. Steps In The Cycle Of Amoeboid MovementExtension
- 27. Contraction of microfilament networks requires Myosin II filaments to make microfilaments slide.Rear of CellContracts
- 28. The ability of myosinto walk on actin
- 29. Steps In The Cycle Of Amoeboid MovementExtension
- 30. Endocytosis and vesicle transport from back to
- 31. Soon-Tuck Sit, and Ed Manser J Cell
- 32. Скачать презентанцию
The Cytoskeleton Includes Dynamic NetworksOf Microfilaments And Microfilaments
Слайды и текст этой презентации
Слайд 1Lectures 21 and 22:
The Cytoskeleton:
Microfilaments
Essential
Cell Biology
Third Edition
Chapter 17
Слайд 3Microfilaments composed of actin are often
found at the cortex of
cells. They also form
cell. Theyare highly dynamic forming networks that
serve as the basis for cellular motility.
Слайд 5Microfilaments (MFs) consist of a double helix
Of actin monomers
Platinum coated
microfilaments in a white blood cell
A single microfilament in vitro
Слайд 7Microfilaments like microtubules have plus and
minus ends that are
not identical. The plus end
favors polymerization. The minus end
favors depolymerization.
Minus End = “pointed end” Plus End = “barbed end”
Слайд 8Animation: Regulation of Actin Polymerization and Depolymerization inside cells
using Profilin and Cofilin
Profilin binds to actin monomers (G-actin) to
aid polymerization; cofilin binds to microfilaments (f-actin) to sever them and allow faster depolymerization 
Слайд 93-D Microfilament Networks Are The Basis Of Dynamic Cell Structures:
Network construction requires accessory proteins that interact with actin
Слайд 10Microfilaments Interact With accessory proteins
(actin binding proteins) In Forming
Networks
or rapid Disassembly of networks
Microfilament
bundling
And crosslinking
proteins
Слайд 11Microfilaments Form Bundles using the crosslinking proteins α-Actinin And Fimbrin
Stress
Fibers Microvilli
Can shorten Can
not shorten
Слайд 13Microfilament
elongation in vivo
is aided by the
accessory proteins
profilin and formin.
Profilin binds
to
ATP- actin and the
complex acts as a
building block.
Thecomplex prevents
nucleation.
Formin binds P-A
complexes and guides
them to the growing
(barbed) end of the Microfilament
Formin
Profilin
Actin
Слайд 15In cells, the ends of microfilaments are capped
with other
proteins to control assembly. ARP 2
and ARP 3 cap
the minus end of microfilaments.
Слайд 16ARPs allow binding of minus ends to other
filaments. In
this way microfilament networks
can be formed that are used
as superstructures for cell shape and motility.
Слайд 19Steps In The Cycle Of Amoeboid Movement
Extension of leading edge
due to actin
Polymerization.
Linking of cell cortex to substratum via
connection of
cortical microfilaments to Adhesion plaques/focal contacts.
3. Rear of cell contracts and moves forward
by interaction of microfilaments with myosin.
4. Microfilaments depolymerize at rear of cell.
Plasma membrane is retrieved by endocytosis.
Actin monomers and membrane vesicles move to
front of cell via microtubules tracks to be reutilized.
Слайд 24Steps In The Cycle Of Amoeboid Movement
Extension of leading edge
due to actin
Polymerization.
Linking of cell cortex to substratum via
connection of
cortical microfilaments to Adhesion plaques/focal contacts.
3. Rear of cell contracts and moves forward
by interaction of microfilaments with myosin.
4. Microfilaments depolymerize at rear of cell.
Plasma membrane is retrieved by endocytosis.
Actin monomers and membrane vesicles move to
front of cell via microtubules tracks to be reutilized.
Слайд 25Focal adhesions use hundreds of transmembrane proteins called integrins for
linking the actin cytoskeleton inside the cell to extracellular matrix
fibers such as collagen outsidethe cell. This linkage has a mechanical function.Focal adhesions are
dynamically controlled allowing them to bind, and unbind from extracellular matrix fibers in a reversible manner. This allows them to serve as temporary anchors during cell movement.
Слайд 26Steps In The Cycle Of Amoeboid Movement
Extension of leading edge
due to actin
Polymerization.
Linking of cell cortex to substratum via
connection of
cortical microfilaments to Adhesion plaques/focal contacts.
3. Rear of cell contracts and moves forward
by interaction of microfilaments with myosin.
4. Microfilaments depolymerize at rear of cell.
Plasma membrane is retrieved by endocytosis.
Actin monomers and membrane vesicles move to
front of cell via microtubules tracks to be reutilized.
Слайд 27Contraction of microfilament networks requires
Myosin II filaments to make
microfilaments slide.
Rear of Cell
Contracts
Слайд 28The ability of myosin
to walk on actin filaments
is due to
a cycle of force
producing conformational
changes that is powered
by ATP hydrolysis.
Thiscycle is the same as in
skeletal muscle.
Слайд 29Steps In The Cycle Of Amoeboid Movement
Extension of leading edge
due to actin
Polymerization.
Linking of cell cortex to substratum via
connection of
cortical microfilaments to Adhesion plaques/focal contacts.
3. Rear of cell contracts and moves forward
by interaction of microfilaments with myosin.
4. Microfilaments depolymerize at rear of cell.
Plasma membrane is retrieved by endocytosis.
Actin monomers and membrane vesicles move to
front of cell via microtubules tracks to be reutilized.
Слайд 30Endocytosis and vesicle transport from back to front.
Depolymerization
And transport of
actin back to front.
Via microtubule network and motor
proteins.
Movement of nucleus,
cytoplasm and organelles back to front viaMyosin-induced movement along sub-nuclear stress fibers.
Слайд 31Soon-Tuck Sit, and Ed Manser J Cell Sci 2011;124:679-683
ADHESION
PLAQUE/
FOCAL
CONTACT
CORTICAL ACTIN LAYER (ANCHORED)
WHILE CELL ORGANELLES MOVE FORWARD
