Cytoskeleton part 2 Flashcards
association of organelles and other cytoplasmic components with cytoskeleton
moves in straight lines
Role of cytoskeleton
organising and controlling movement of some organelles
saltatory movement
rapid bursts then pauses
cellulose biosynthesis
protein complexes moves straight lines along filamentous pathway
cytosolic ribosomes
found associated with protein filaments
soluble enzymes
found in association with actin filaments in myofibrils and in stress fibres of fibroblasts
motor proteins
microtubules motor using ATP derived energy
2 groups of motor proteins
kinesin and dyneins
kinesin
move to positive end
dynein
moves to negative end
examples of movement along MT
for transporting vesicles
integrity and reassembly of Golgi apparatus
2 conformation that alternates motor protein
conformation stabilised by bound ATP, other by ADP and hydrolysis
dynein function
cycling of conformational changes allow ‘shuffling’ along filament
microtubule provide tracks for…
movement of vesicles along axons
anterograde transport
movement from negative to positive from cell body
retrograde transport
movement from positive to negative from axons - return
time take during rapid transport
3mm/s , 250mm/day
slow transport
1mm/day
directionality of movement
due to polarity from positive to negative end in MT and MF
movement without polarity
motor proteins move randomly
globular head region
engages filaments and actively moves along it
tail region
point attachment of motor protein and its cargo
power stroke
ATP hydrolysis - conformational change
thrusting head backwards - tension in tail
tail and cargo moves forward
recovery stroke
occurs when protein loosely attached to filaments
head slides along by thermal motion/diffusion
what all stroke powered by
hydrolysis
kinesins contain
dimer of heavy and light chain = tetrameric structure
3 domain
large globular head
stalk
small globular head
myosin function
as motor protein on actin filaments
myosin V
vesicles and organelle transport
myosin XI
movement - cytoplasmic streaming
mobility and cytoskeleton requires
anchorage
active cytoskeleton
function of mobility and cytoskeleton
able to anchor itself in body - other extracellular components
net synthesis at leading edge, retraction at other end
actin filaments in migrating cells
organisation varies significantly in different areas of cell
leading edge
more organised and elongate forming net migration
cilia diameter
200nm in diameter
A tubule in cilia
has 13 protofilaments
B tubule in cilia
has 10/11 protofilaments
central pair in cilia
13 protofilaments
9 + 2 pattern
9 (made from A and B tubule) around the outside and 2 complete MT
how cilium moves - primary force
ATP driven cyclic movement of ciliary dynein
cytoskeletons in cell division
for position, control of MT
have accurate partitioning of chromosomes division
membrane - cytoskeleton interaction
connectivity from outside to inside
method of interacting between cytoskeleton and plasma membrane
indirect vie specific group of actin binding protein
Ezrrin-Radixin Moesin
signal activation of ERM interaction with actin
signal causes
dissociation between MF and transmembrane protein binding
extracellular component
interact indirectly vis integrin bind to talin - indirectly attach to actin
cytoskeletal disorder
muscle cell membrane, dystrophin, dystrophin associated protein complex
dystrophin
inside of cell and binds actin and N-terminus
different mutation
causes different muscular dystrophin
type 1 interaction
ABPs bind to membrane via interaction with lipd
type 2 interaction
integral membrane proteins
type 3 interaction
ABPs that associate with integral membrane protein
outer doublet in cilium
A and B tubules
