Maturation promoting factor 622503 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]]