Maturation promoting factor
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213301104
2008-05-18T19:07:22Z
Thijs!bot
1392310
robot Adding: [[hu:MPF]]
[[Maturation promoting factor]] (abbreviated '''MPF''', also called '''mitosis-promoting factor''' or '''M-Phase promoting factor''') is a [[dimer|heterodimeric]] [[protein]] composed of [[cyclin|cyclin B]] and [[cyclin-dependent kinase]] ([[Cyclin-dependent kinase|CDK1]], also known as Cdc2 or p34 kinase) that stimulates the [[mitosis|mitotic]] and [[meiosis|meiotic]] [[cell cycle]]s. MPF promotes the entrance into mitosis from the [[G2 phase]] by phosphorylating multiple proteins needed during mitosis. MPF is activated at the end of G<sub>2</sub> by a [[phosphatase]], which removes an inhibitory phosphate group added earlier.
MPF is made of 2 subunits:
* a subunit that transfers phosphate groups from [[Adenosine_triphosphate|ATP]] to specific [[serine]] and [[threonine]] residues of specific proteins ([[kinase]] activity)
* [[cyclin]], a regulatory subunit
Targets of MPF include:
* [[condensin]]s, which enable [[chromatin]] condensation (see [[prophase]])
* various [[microtubule]]-associated proteins involved in [[mitotic spindle]] formation
* [[lamin]]s, interaction contributing to degradation of the [[nuclear envelope]]
* Histones, H1 and H3
* Golgi matrix, to cause fragmentation
==Inhibition of myosin==
MPF phosphorylates inhibitory sites on [[myosin]] early in mitosis. This prevents [[cytokinesis]]. When MPF activity falls at anaphase, the inhibitory sites are dephosphorylated and cytokinesis proceeds.
==Disassembly by APC==
MPF is disassembled when [[anaphase-promoting complex]] (APC) polyubiquitinates cyclin B, marking it for degradation.
==External links==
* {{MeshName|Maturation-Promoting+Factor}}
{{Cell-biology-stub}}
{{Cell cycle proteins}}
[[Category:Cell cycle]]
[[hu:MPF]]