Condensed prometaphase chromosomes Condensed prophase chromosomes Phosphorylated condensin I promotes condensation of prometaphase chromosomes Authored: Orlic-Milacic, M, 2012-10-12 Edited: D'Eustachio, P, 2012-10-19 Edited: Matthews, L, 2012-10-18 Pubmed11136719 Pubmed15146063 Pubmed15572404 Pubmed17066080 Pubmed17356064 Pubmed18977199 Pubmed19481522 Pubmed21498573 Pubmed9774278 Reactome Database ID Release 432520883 Reactome, http://www.reactome.org ReactomeREACT_150278 Reviewed: Kalitsis, Paul, 2012-11-12 While condensin II complex (consisting of subunits SMC2, SMC4, NCAPD3, NCAPG2 and NCAPH2), responsible for condensation of chromosomes in prophase (Hirota et al. 2004, Abe et al. 2011), is nuclear, condensin I is cytosolic and gains access to chromosomes only after the nuclear envelope breakdown at the start of prometaphase (Ono et al. 2004). Condensin I, activated by CDK1 phosphorylation (Kimura et al. 1998, Kimura et al. 2001, Takemoto et al. 2006, Murphy et al. 2008), promotes further condensation of chromosomes in prometaphase and metaphase, visible as longitudinal chromosome shortening (Hirota et al. 2004). Besides CDK1-mediated phosphorylation, association of condensin I with chromosomes may be regulated by AURKB (Lipp et al. 2007). In budding yeast, condensin phosphorylation by Cdc2 (CDK1 ortholog) is followed by Cdc5-mediated phosphorylation (Cdc5 is PLK1 ortholog), which is important for the sustained mitotic activity of condensin complex (St-Pierre et al. 2009). Phosphorylation by PLK1 is also important for the activation of human condensin II complex (Abe et al. 2011).