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Definition
| family, binds actin monomers, in similar conc. as the G-actin, it provides a buffering effect for actin, b/c the free actin would otherwise uncontrollably polymerize – b/c of a high association constant for actin- blocks actin from going to ATP |
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Definition
- microvilli (enterocyte 200 nm diameter, 1 um tall) filipodia
- pseudopodia & lamellipodia (movement)
- tight junctions, adherens junctions, focal contacts
- stress fibers (parallel aggregates for cell shape and orientation – might form w/o enough actin)
- cortical cytoskeleton (provide stiffness, structure, and shape to the membrane)
- epithelial curvature (to bend into structures like the neural tube)
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| catalyze extension, binds to actin-ADP more tightly than Thymosin – only when properly signaled to- and binds it so that actin-ADP can exchange for ATP |
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catalyze extension, binds to the actin chain and to incoming actin-profilin- ATP complexes -2 active sites – one holds onto the filament while one binds to actin-profilin complex [image][image] |
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| creates tight crosslinks for bundles (microvilli, pseudopodia, stress fibers, filopodia, lamellipodia) |
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| creates looser crosslinks between opp. oriented microfilaments to leave room for myosin II (contraction) |
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| forms networks which fills in cytoplasm (gels) & binds MF to integral membrane proteins |
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| Cofilin, severin, & gelsolin |
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Definition
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| (actin-related protein – 7 families– ARP1 to ARP8 [no ARP7]) – seven protein complex that nucleates a new microfilament or a branch |
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responsible for moving vesicles and other cargo on microfilaments, always towards the + end singular head binds to actin, tail binds cargo Myosin I is in microvilli
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responsible for contractile forces The tails bind to opp. oriented actin so that the 2 heads are in diff. directions walks towards + end [image][image] |
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Definition
| an ERM protein localized to microvilli- it can be active or inactive and is regulated by intra- and extracellular signals. In the active state, it binds to a MF and to an integral membrane protein of the membrane. In the inactive state, the 2 ends binds together. This in one way a MF can attach to the membrane. |
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Definition
| muscle protein that binds MF to proteins in the membrane (sarcolemmal membrane). If mutated or absent – result is Duchenne’s muscular dystrophy. This causes loss of links between cortical cytoskeleton and the extracellular matrix – so muscles begin to rip. |
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Term
Smooth Muscle Contraction (Phosphorylation Regulation) |
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Definition
- If myosin is not phosphorlated then the tail coils up and wraps over the head which blocks myosin from binding to other myosins or from binding to actin – this is if calcium is low
- If myosin light chain kinase is activated by calcium bound to calmodulin, it phosphorylates the myosin
- The phosphorylated myosin can then form a thick filament by binding the tail the other myosins and then it can walk along the actin – it pulls the dense bodies together
- When it is active(contraction)- the myosin pulls the actin together and it moves the dense bodies together (actin is attached to dense bodies)
- Most blood pressure medication functions by making smooth muscle relax
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Term
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Definition
- intracellular transport
- organelle/IF placement: Placed by MT- centrosomes and the golgi are near the nucleus, and rough ER by the membrane
- position and move chromosomes (move to poles) during mitosis/meiosis
- Cores (axonemes) of cilia, flagella, and centrioles
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Term
| MTOC – MT organizing center |
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Definition
the centrosome (-) End of MT is buried in the centrosome -
- triplet – 2 B tubules (10 subunits) instead of 1 and 1 A tubule (13 subunits)
- organizes mitotic spindle
- and proteinaceous material w/ gamma-tubulin (nucleates and caps the – end)
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Term
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Definition
- Cells generally have 1 or more cilia – not always motile (more in the trachea [lung] and oviduct)
- Cilia and Flagella are doublets, with one containing 13 (A tubule) and the other circle containing 10 protofilaments (B tubule)
- Axoneme – 9 doublet MTs oriented identically on the outside ring w/ 2 singlet MTs and an inner sheath in the core w radial spokes that connect. Dyneins move the cilia and central area rotates –movement is not clear. + end is at the tip and – end in the basal bodies (similar to centrosome)
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Definition
(oncoprotein 18 or op18) [MT destabilizer] regulates tubulin polymerization - When phosphorylated – it does NOT bind tubulin and so stimulates MT formation
- Stathmin is phos. during mitosis so the spindle can form, after cytokinesis it is dephos. to prevent further spindle formation (GTP hydrolysis catches up)
- Cells with stathmin knockouts – similar to cancer cells- have abnormal cell cycles. In mice- makes them less fearful.
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Definition
| (family of protein) move to +end of MT (some can move to the – end) , to membrane of cell |
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| (family of protein) move to – end of MT, to the centrosome of cell, and move cilia and flagella |
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tail helps hold dynein to the MT amyotrophiclateralsclerosis disease- one of them is a mutation in dynactin- patient cannot get trophic substance back to the cell body |
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Definition
MT associated protein stabilize, cap, adhere to other cytoskeleton, motors, the TAU protein is a MAP |
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Term
retrograde transport anterograde transport |
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Definition
- Dynein – back to cell body- retrograde transport
- Kinesin- along the MT –anterograde transport
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Term
Families of IF (tonofilaments) nerve cells epithelial cells muscle cytoskeleton of nuclear envelope cells of mesenchymal origin glial cells |
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Definition
- Neurofilaments (nerve cells)
- NF-L (light), NF-M (medium), NF-H (heavy) – the weight refers to the extra weight on the globular ends and spaces them differently – the L will be closest together – makes regular spacing. There are a lot more of these than MT in an axon.
- Keratins type I (acidic) and type II (basic) (epithelial cells and their derivatives – hair and nails)
- Desmins (Muscle)
- Lamins A, B, and C (cytoskeleton of nuclear envelope and binds to chromatin)
- 1st kind of IF – all eukaryotes contain lamins
- Vimentin (cells of mesenchymal origin)
- Glial fibrillary acidic protein -GFAP (glial cells)- brain cell
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Term
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Definition
- Structural integrity – primary function
- Cell-cell: desmosomes
- Cell-matrix:hemidesmosomes
- Intracellular: neuronal axon stabilization
- Nuclear: stability or lability of the nuclear envelope
- mitosis- when the lamins are phosphorylated by the cdck enzyme they are labile – after telophase phos. is reversed and the envelope reforms
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Term
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Definition
connect the basal membrane of an epithelial cell to an underlying membrane/connective tissue - Contains:
- transmembrane proteins to function as receptors for extracellular matrix
- adaptor proteins that connect to transmembrane proteins and IFs and other adaptors
- Bullous Pemphigoid Antigen 1 and 2 – cell adhesion complexes- named after blistering disease
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