Centralspindlin is a motor complex implicated in cell division. It contributes to virtually every step in

cytokinesis Cytokinesis () is the part of the cell division process and part of mitosis during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division ...

,Glotzer, Michael
"Cytokinesis: Centralspindlin Moonlights as a Membrane Anchor"
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Current Biology ''Current Biology'' is a biweekly peer-reviewed scientific journal that covers all areas of biology, especially molecular biology, cell biology, genetics, neurobiology, ecology, and evolutionary biology. The journal includes research artic ...

'', 18 February 2013 It is highly conserved in animal cells as a component of the spindle midzone and midbody.Glotzer, Michae
" The 3Ms of central spindle assembly: microtubules, motors and MAPs"
''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'', January 2009 Centralspindlin is required for the assembly of the mitotic spindleNature Publishing Group
"Research Highlights"
''Cell Migration Consortium'', 2009. Retrieved on 01 March 2014. as well as for microtubule bundling and anchoring of midbody microtubules to the plasma membrane. This complex is also implicated in tethering the spindle apparatus to the plasma membrane during cytokinesisLekomtsev et al

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'', 13 December 2012 This interaction permits cleavage furrow ingression. In addition, centralspindlin's interaction with the ESCRT III allows for abscission to occur.

Structure

Centralspindlin is a heterotetramer consisting of two different subunit proteins: # A

KIF23 KIF may refer to: * Koyamada International Foundation (Shin Koyamada#Koyamada International Foundation , KIF), an international nonprofit organization * KIF Kolding, a handball club in Denmark * Kif Kroker, a character in the TV show ''Futurama'' * ...

dimer (Kinesin 6 motor protein, also known as MKLP1 in mammals and ZEN-4 in ''C. elegans'') ::Consists of a motor domain linked to a parallel coiled coil and a globular region by a linker # A RACGAP1 dimer (Also known as MgcRacGAP in mammals or CYK-4 in ''C. elegans'') ::Contains a coiled-coil and an important RhoGAP domain Both KIF23 and RacGAP1 dimerize via their parallel coiled coil domain.Pavicic-Kaltenbrunner et al
"Cooperative assembly of CYK-4/MgcRacGAP and ZEN-4/MKLP1 to form the centralspindlin complex"
''Molecular Biology of the Cell'', 17 October 2007 Centralspindlin oligomerizes in order to link the mitotic spindle with the plasma membrane The sequences mediating interactions between KIF23 and RacGAP1 are highly variable between species. However, a high affinity interaction between these subunits is essential for the proper functioning of the Centralspindlin complex.

Subunits

KIF23 interacts with microtubules at sites of overlap, linking the centralspindlin complex to the mitotic spindle. RacGAP1 recruits

ECT2 Protein ECT2 is a protein that in humans is encoded by the ''ECT2'' gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed ...

to the central spindle. ECT2 is a Guanine nucleotide-exchange factor for

RhoA Transforming protein RhoA, also known as Ras homolog family member A (RhoA), is a small GTPase protein in the Rho family of GTPases that in humans is encoded by the ''RHOA'' gene. While the effects of RhoA activity are not all well known, it is ...

. Cytokinesis is initiated when RhoA is activated by ECT2.Tatsumoto et a
"Human Ect2 Is an Exchange Factor for Rho Gtpases, Phosphorylated in G2/M Phases, and Involved in Cytokinesis"
''

Journal of Cell Biology The ''Journal of Cell Biology'' is a peer-reviewed scientific journal published by Rockefeller University Press. History In the early 1950s, a small group of biologists began to explore intracellular anatomy using the emerging technology of e ...

'', 29 November 1999 RacGAP1 is also involved in tethering the central spindle to the plasma membrane. Without this interaction, cytokinesis cannot occur.

Interactions

*A glance at the busy complex *Interacts with RhoA and Rac during furrow ingressionYuce et al
"An ECT2–centralspindlin complex regulates the localization and function of RhoA"
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'', 15 August 2005 *Recruits cytokinetic effector proteins such as ECT2Gene Editing Rat Resource Cente
"Gene-Term Annotation Report"
Retrieved on 01 March 2014 *Binds microtubule plus-end overlaps characteristic of the central spindle through its KIF23 subunit *Recruits the ESCRT III complex in late cytokinesis *Promotes cortical accumulation of F-actin and myosin through its RACGAP1 subunit *Stabilized through interactions with Aurora B kinaseDouglas et al
"Aurora B and 14-3-3 Coordinately Regulate Clustering of Centralspindlin during Cytokinesis"
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'', 25 May 2010 *Negatively regulated by

14-3-3 14-3-3 proteins are a family of conserved regulatory molecules that are expressed in all eukaryotic cells. 14-3-3 proteins have the ability to bind a multitude of functionally diverse signaling proteins, including kinases, phosphatases, and tran ...

*RacGAP1 binds to PRC1 microtubule crosslinker, an interaction that is crucial for maintaining the stability of the spindle midzone.

References

{{Reflist Cell biology