spatial control of cell division Flashcards
what is cell division needed for
growth, healing and replacing old cells
how many cells are in your body
~10 trillion
how often are your whole body of cells replaced
1x a year
what are the steps in the cell cycle
M phase, G1, S and G2
what do CDKs do
they phosphorylate
what to cyclins do
tell the CDKs what to phosphorylate (recruit the CDK to the right substrate) (when the cyclin changes, you phosphorylate different proteins in the cell to control different processes)
what does securin do
stops protein seperates from being degraded - promotes seperation
what does Mps1 kinase do
activates the mitotic checkpoint by localising to the outer kinetochore region to produce a signal
what do kinetochores do
produces w signal within the mitotic checkpoint to produce a mitotic checkpoint complex (MCC) which is 4 proteins assembled into a complex
what does aurora b kinase do
it is localised in a centromere during error correction
what do centromeres do
they phosphorylate the binding sites of microtubules within error correction to destabilise the incorrect microtubule attachments
what are Mps1 kinase and aurora B kinase both controlled by
space
what are the stages in the mitotic checkpoint
- mps1 kinase localises to a kintetochore
- mps1 recruits other proteins and assembles them into an inhibitory complex (MCC)
- MCC inhibits a large ubiquitin ligase needed for the mitotic exit (the anaphase promoting complex)
- microtubule attach and the checkpoint signal gets shut down
what does mps1 interact directly with
the NDC80 complex in vitro
what is the NDC80 complex required for
microtubules to bind kinetochores
what do microtubules compete off in vitro
the mps1-ndc80 interaction
what enables rapid checkpoint silencing
competition between ndc80 and mps1 for microtubules
what are the stages in error correction
- aurora b kinase localises to the centromere
- phosphorylates the kinetochore to remove microtubules (electrostatic charge)
- kinetochores under tension are removed away from aurora b activity, therefore they are stabilised
what can be used to measure live kinase activity
FRET reporters
centromemre phosphorylation is the same irrespective of what
microtubule attachment
what is reduced upon microtubule attachment
kinetochore phosphorylation
what happens if the mitotic checkpoint goes wrong
chromosome gain/loss
what happens if error correction goes wrong
chromosome damage (during cell separation at cytokinesis)
what are frequently seen in tumour cells
mitotic errors
