Microtubules Flashcards
What MT contain
alpha-tubulin and beta-tubulin
MT characteristics
high degree of sequence similarity
found in plant and animal cell
alpha tubulin
bound molecule GTP
doesn’t hydrolyse
beta tubulin
may have bound GTP/GDP
assemble of MT
110kDa heterodimer - polymerising subunit
polymerisation of MT
tubular structure with 25nm in diameter and 14nm internal pore
formation
starts with nucleating
go in +ve direction
polymerisation driven
by GTP hydrolysis
depolymerisation driven
by release of tubulin dimers
regulation of MT assembly - favourable
polymerisation of free tubulin subunit
function of stathmin
binds to 2ab tubulin dimers as it reduces free pool and MT elongation
regulation of MT assembly method
- GTP hydrolysis catch up with subunit addition due to loss of GTP cap
- transition from growing and shrinking state
- cause loss of subunit and recycles
how contributing to dynamic nature of MT
controlling availability of subunits controls MT elongating or contracting
Y-tubulin ring complex matrix
organised by pair of centriole
for microtubule growth
stabilisation of MT
create spacing of MT
MAP2
defines length between microtubules
Tau
2 binding point - A and C terminus
extension not as long as MAP2
Intermediate filaments - characteristic
most stable component
least soluble constituent
IF made up of
individual monomers coiled up
has helical structure
fibrous polypeptide - how assembled
side by side = rise to F with high tensile strength
size of fibrous polypeptide
vary from 40kDa to 200kDa
different fibrous polypeptide
different cell types between same cell type in different species
non-helical region
stabilises filament and interact with other components of cytoplasm
IF variable
likely to confer cell type specific function
