{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


Micro-_and_intermediate_filaments - Microfilaments...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Microfilaments Structure Flexible, helical fibres of ~7 nm diameter G-actin Central cavity binds ATP or ADP F actin 37 + end (faster growth) BIO 1140 – SLIDE 1 F-actin Polymer of G-actin monomers Helix Filament has polarity Fig. 2.22 - end G-actin + ADP Dissociates readily G-actin + ATP Polymerizes readily Dynamic character ATP-G-actin polymerizes more readily than ADP-G-actin Hydrolysis follows polymerization ADP-G-actin dissociates more readily than ATP-G-actin Treadmilling Actin-binding proteins regulate the rate and form of polymerization and BIO 1140 – SLIDE 2 Fig. 9.65, Karp et al. 2010 network formation Cell signalling mechanisms regulate actin-binding proteins Useful drugs Cytochalasin Phalloidin Functions Shape/support Cell cortex - networks Microvilli - bundles Adherens junctions BIO 1140 – SLIDE 3 Fig. 15-18, Becker et al. 2009 Fig. 17-2, 17-29, Alberts et al. 2004 - smallest set of skeletal element - supermolecular structure - complex of proteins - building block is monomer of actin - many diff isoforms of actin - highly conserved -- can take actin from two different species and they can polymerize together - actin takes U shaped form - link to other actin monomers - link the same way - gives polarity - - end --- + end is where the microfilament grows - new monomers are added there - two helices wind around each other - monomer of actin - is called G-actin -when stringed together - called F-actin - if ATP is bound to G-actin - polymerizes more quickly --- more likely to be hydrolyzed to ADP-G-actin - once hydrolyzed will be more readily dissociated - monomer sequestering proteins - decrease the likelihood of getting a microfilament - microfilament - more likely to form spontaneously compared to microtubules - proteins that cap the + end - prevent it from growing - protein that help microfilament form arrays or bundles - proteins that bind the filament to the cell membrane - also proteins that depolymerize the filament Cytochalasin - monomer sequestering compound - prevents actin from polymerizing - higher likelihood of microfilaments breaking down --- has similar effect on filaments that Choloisin has on microtubules Phalloidin - stabilizes microfilaments - comes from deathcap fungus --- same effect on filaments that Taxon has on microtunules ---- both from fungus - cell cortex - important in supporting cell membrane - often linked to cell membrane to provide supporting structure -- particularly in animal - but can also be found in some organisms with cell walls ex. fungi
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}