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Free online life science study material. To continue with cell cycle
In the M or mitotic phase the CDK1 cyclin B complex also phosphorylate component of nuclear pore and some protein of inner nuclear membrane.so choromosome is unable to bind to inner nuclear membrane and whole structure gets disorganized.
Protein of nuclear pore are imbibed by endoplasmic reticulum and golgi bodies also get fragmented.
Endoplasmic reticulam remains intact.
Centrosome also gets phosphorylated and repell each other.
Microtubule associated proteins are target of CDk1-cyclin B compex, so microtubule also get disorganized.
Microtubule associated protein (MAP) are present on the cytoplasm periphery initialy prior to cell division.
At metaphase Anaphase promoting Complex (APC) is present, which is a ubiquitin ligase.
If APC is inactive, cell do not proceed to cell division and gets activated only when choromosmes are properly alligned to spindle fibre.
If they are not alligned properly, Mad and Bub protein bind to kinetocore and lead to inhibition of APC.
Active APC have two targets:
1. APC bind ubiquitin to securin and cohesin gets degraded by separase enzyme.The securin subunit is attached to separase enzyme and APC act on securin to detach from separase.
2. Cyclin B is target of APC and gets deactivated by APC.
APC inactivated in late G1 phase by Gi/S CDKs.
CDKs are regulated by phosphorylation and dephosphorylation. It is activating phosphorylation at some sites and activating dephosphorylation on the other sites.
A threonin of CDK at 160 position requires phosphorylation and is phosphorylated by CAK= CDK activating kinase.
At 14 and 15 th position threonina nd tyrosin are phosphorylated respectively, they require dephosphorylation for activation and this is done by cdc25 phosphatase.
At 14 and 15 th position during inactive state they are phophorylated by wee1 kinase to make them inactive.
This ends the topic cell cycle regulation.
Hope this will help you all. See you all with next topic.
Thnkyou for reading.
Free online life science study material. To continue with cell cycle
In the M or mitotic phase the CDK1 cyclin B complex also phosphorylate component of nuclear pore and some protein of inner nuclear membrane.so choromosome is unable to bind to inner nuclear membrane and whole structure gets disorganized.
Protein of nuclear pore are imbibed by endoplasmic reticulum and golgi bodies also get fragmented.
Endoplasmic reticulam remains intact.
Centrosome also gets phosphorylated and repell each other.
Microtubule associated proteins are target of CDk1-cyclin B compex, so microtubule also get disorganized.
Microtubule associated protein (MAP) are present on the cytoplasm periphery initialy prior to cell division.
At metaphase Anaphase promoting Complex (APC) is present, which is a ubiquitin ligase.
If APC is inactive, cell do not proceed to cell division and gets activated only when choromosmes are properly alligned to spindle fibre.
If they are not alligned properly, Mad and Bub protein bind to kinetocore and lead to inhibition of APC.
Active APC have two targets:
1. APC bind ubiquitin to securin and cohesin gets degraded by separase enzyme.The securin subunit is attached to separase enzyme and APC act on securin to detach from separase.
2. Cyclin B is target of APC and gets deactivated by APC.
APC inactivated in late G1 phase by Gi/S CDKs.
CDKs are regulated by phosphorylation and dephosphorylation. It is activating phosphorylation at some sites and activating dephosphorylation on the other sites.
A threonin of CDK at 160 position requires phosphorylation and is phosphorylated by CAK= CDK activating kinase.
At 14 and 15 th position threonina nd tyrosin are phosphorylated respectively, they require dephosphorylation for activation and this is done by cdc25 phosphatase.
At 14 and 15 th position during inactive state they are phophorylated by wee1 kinase to make them inactive.
This ends the topic cell cycle regulation.
Hope this will help you all. See you all with next topic.
Thnkyou for reading.
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