Emma Allde
Mind Map by , created more than 1 year ago

Medicine Y1 (Theme 1 | Cells and organelles) Mind Map on Th1L06 Actin, created by Emma Allde on 16/08/2016.

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Emma Allde
Created by Emma Allde over 8 years ago
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Th1L06 Actinpart of the cytoskeleton along with IF and MTnetwork of protein filaments that extendthroughout the cell that determine:cell shape and polaritytissue structureadhesioncell movementintracellular movement (of vesiclesand of chromosomes)structuremicrofilamentcomposed of actin-binding proteins5% total proteincalled F-actinfilamentous actin or microfilamentpolymers of individual actin proteinscalled G-actin (globular actin)polarised doublehelix13 actin subunits for everycomplete turn7nm diameterGrowth(1) requires ATP to be bound to the actinmonomer (G-actin)very dyanmicmonomers can be added and removed fromboth ends of the polymerG-proteins add more rapidly to (+) end ofthe filamentonce incorporated, ATP is hydrolysedto ADPG-protein is removed more rapidlyfrom the (-) end of the filamentNot very stable over timeATP eventually hydrolyses to ADP and willdepolarise and come off at the negative endFunctionprovidesupportMaintains the shape of cellsabsorption in the gut by forming an adhesion belterythrocytesmicrovilli in gutdetect vibration in the cochleaIn sterocilliacells are depolarised or hyperpolarised by deflectionscaused by sound; actin filaments keep them rigidCell migrationmodulate polymerisation dynamics and functione.g. myosin, capping proteins, severin, etc.required to hold synaptic vesicles close to the presynaptic membraneessential to anchor cells to each otheressential to anchor cells to anchor extracellular matrix at cell junctionsCell motilitye.g. migration of neutrophils (WBC) to sites of infection for phagocytosisfour events(1) cell pushes out protrusions at the front(leading edge) ā—‹ actin filament polymerisationprovides to force of membrane protrusion(2) ā—‹ protrusions adhere to thesurface on which the cell is movingthrough contact junctions; F-actinconnects to the focal adhesions toprovide a contractile force for the cell(3) the rest of the cell pulls against theanchorage points to drag itself forward(4) actin depolymerises at the rearLamellipodiacytoskeletal protein actin projection on theleading edge of the cellextend and withdrawgenerated by rapid growth of actinfilaments at the cell membranethe (+) end of actinfilaments are orientedtowards the peripheryDouble click this nodeto edit the textClick and drag this buttonto create a new node