Cdks Flashcards
What does cdk stand for?
Cyclin dependent kinase
How does a cdk become activated?
- cyclin can bind and pull the activation loop away from active site (expose ATP molecule to give access to other molecules/targets)
- for full activation important threonine residues need to be phosphorylated in T/activation loop- phosphorylated by CAK
How do target proteins bind to cdks?
Bind to the active site
- the serine/threonine target side chains are positioned with respect to gamma phosphate of ATP
what time of kinase is a cdk?
serine/threonine kinase
how many cdks are there in yeast and mammals?
Yeast - only 1 cdk (cdk1) (differences due to changes in cyclins)
Mammals - 4 cdks (1,2,4,6)
how can cdks be controlled/regulated?
by cdk regulators
- activators (mainly cyclins, CAK)
- inhibitors (CKIs)
what stage of the cell cycle do CKIs usually operate?
mainly in G1 and S
give some examples of CKIs
- P21cip
- P27kip
- p15ink4b
what is the other name for CAK?
cdk7-cyclin H complex
where abouts on cdk1 is the inhibitory phosphoylation?
- 2 adjacent inhibitory phosphorylations must occur
- 14 threonine and 15 tyrosine (T14/Y15)
what carries out the 2 adjacent phosphorylations?
dual specific kinases
e.g. wee1 kinase
how are the inhibitory phosphates removed?
removed by cdc25 (a phosphate)
what does activated cdc2 induce?
induces entry into mitosis (CdK1)
what cdk/cyclin complex is the s-phase?
cyclinA - cdk1/2
what cdk/cyclin complex is the m-phase?
cyclin B - cdk1
