advanced cell biology. lecture...
TRANSCRIPT
![Page 1: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/1.jpg)
Advanced Cell Biology. Lecture 38
Advanced Cell Biology. Lecture 38
Alexey Shipunov
Minot State University
April 30, 2012
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Advanced Cell Biology. Lecture 38
Outline
Questions and answers
Cytoskeleton
Structure of cytoskeleton
![Page 3: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/3.jpg)
Advanced Cell Biology. Lecture 38
Outline
Questions and answers
Cytoskeleton
Structure of cytoskeleton
![Page 4: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/4.jpg)
Advanced Cell Biology. Lecture 38
Outline
Questions and answers
Cytoskeleton
Structure of cytoskeleton
![Page 5: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/5.jpg)
Advanced Cell Biology. Lecture 38
Questions and answers
Previous final question: the answer
How do researchers use constantly active Ras protein?
I For determining sequence of proteins in a signal pathway
![Page 6: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/6.jpg)
Advanced Cell Biology. Lecture 38
Questions and answers
Previous final question: the answer
How do researchers use constantly active Ras protein?
I For determining sequence of proteins in a signal pathway
![Page 7: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/7.jpg)
Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Cytoskeleton
I Filament-like: intermediary filaments and actin filamentsI MicrotubulesI All are polymers of proteins
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Intermediate filaments
I Keratin in epithelial cellsI Vimentin in connective-tissue cellsI NeurofilamentsI Nuclear laminsI Strengthening cell
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Strengthening of cell layer
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Microtubules
I Grow from centrosomeI Form flagella or ciliaI Form mitotic spindleI Organize interior of cellI Drive intracellular transport
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Microtubules
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Growth and shrinking of microtubules
I Microtubule is made of 13 tubulin microfilaments, eachcontain pairs of β-tubulin (– end) and α-tubulin (+ end)
I Tubulin dimers bind GTP and form a growing GTP cap ofmicrotubule; if GTP cap is lost, microtubules start to shrink
I Capturing the plus end will stabilize microtubule
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Growing and shrinking of microtubules
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Microtubule-specific drugs
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Centrosomes
I γ-tubulin rings: starting places of microtubule growthI Two perpendicular centrioles (they are similar to basal
bodies of flagella)I Cetrosome has a fisherman-like behavior: microtubules
are constantly growing out of it, then degrading, but someare stabilizing
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Motor proteins
I Kinesins and dyneins are dimers that hydrolyze ATP andmove
I They can move molecules and even whole organelles
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Kinesin and dynein
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Organelle movement movie
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Flagella/cilia
I Hairlike structures growing from cytoplasmic basal bodiesI Contain 9×2 + 2 microtubules connected by dynein armsI They are natural oars
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
9 × 2 + 2 structure of flagella
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Flagella bending
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Actin filaments
I Fast-growing and unstable, they need to contact withmultiple protein types (e.g., capping proteins stabilize actinends)
I Actin filaments are polar, but thinner and shorter thanmicrotubules, ATP-binding
I Allow cell to change its form
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Growing and shrinking of actin filaments
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Actin binding proteins
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Cell crawling
I Web of growing actin filament will push the leading edge ofpseudopodium forward
I ARPs are starting poins of new filaments, formins promotefilament growing
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Formation of pseudopodium
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Myosin
I Two subfamilies of ATP-binding motor proteinsI Myosin-I have one head and one tail, myosin-II (in muscle
cells) are two-headedI GTP-binding Rho proteins activate actin polymerization
and subsequently the movement of cell
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Myosin-I
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Myosin-II
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Final question (1 point)
What will happen with cell if microtubuleswill not be able to grow?
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Final question (1 point)
What will happen with cell if microtubuleswill not be able to grow?
![Page 34: Advanced Cell Biology. Lecture 38ashipunov.info/shipunov/school/biol_250/2011_2012/lec_250-38.pdf · Advanced Cell Biology. Lecture 38 Structure of cytoskeleton Actin filaments I](https://reader033.vdocument.in/reader033/viewer/2022041713/5e49903b2131e21b7a25325c/html5/thumbnails/34.jpg)
Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
Summary
I Intermediary filaments are polymers of ropelike polymersof fibrous proteins
I Microtubules are labile hollow tubes of tubulin, kinesinsand dyneins move along microtubules
I Actin filaments are helical polymers of actin; myosins movealong actin
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Advanced Cell Biology. Lecture 38
Structure of cytoskeleton
For Further Reading
A. Shipunov.Advanced Cell Biology [Electronic resource].2011—onwards.Mode of access: http://ashipunov.info/shipunov/school/biol_250
B. Alberts et al.Essential Cell Biology. 3rd edition.Garland Science, 2009.Chapter 17.