Ska2 (spindle and kinetochore associated complex subunit 2), also known as FAM33A, is a 121 amino acid component of the Ska1 complex, a microtubule-binding subcomplex of the outer kinetochore that is critical for proper chromosome segregation. The Ska1 complex is a component of the kinetochore-microtubule interface and directly associates with microtubules as oligomeric assemblies. Localized to the outer kinetochore and spindle microtubules during cell proliferation, Ska2 is essential for spindle checkpoint silencing and exit from mitosis. Downregulation of Ska2 leads to delayed recruitment of MAD2, a component of the mitotic spindle checkpoint, to several kinetochores resulting in occasional loss of individual chromosomes from the metaphase plate. Ska2 is encoded by a gene located on human chromosome 17, which comprises over 2.5% of the human genome and encodes over 1,200 genes.
Function:
Component of the SKA1 complex, a microtubule-bindingsubcomplex of the outer kinetochore that is essential for properchromosome segregation. Required for timely anaphase onset duringmitosis, when chromosomes undergo bipolar attachment on spindlemicrotubules leading to silencing of the spindle checkpoint. TheSKA1 complex is a direct component of the kinetochore-microtubuleinterface and directly associates with microtubules as oligomericassemblies. The complex facilitates the processive movement ofmicrospheres along a microtubule in a depolymerization-coupledmanner. In the complex, it is required for SKA1 localization.
Subunit:
Component of the SKA1 complex, composed of SKA1, SKA2 andSKA3. Forms a heterodimer with SKA1; the heterodimer interactingwith SKA3. The core SKA1 complex is composed of 2 SKA1-SKA2heterodimers, each heterodimer interacting with a molecule of theSKA3 homodimer. The core SKA1 complex associates with microtubulesand forms oligomeric assemblies. Interacts directly with SKA1.Binds directly to microtubules; but with a much lower affinity thanSKA1. May interact with NR3C1; the relevance of such interactionremains unclear in vivo.
Subcellular Location:
Cytoplasm, cytoskeleton, spindle.Chromosome, centromere, kinetochore. Note=Localizes to the outerkinetochore and spindle microtubules during mitosis in a NDC80complex-dependent manner. Localizes to both the mitotic spindle andkinetochore-associated proteins.
Similarity:
Belongs to the SKA2 family.
SWISS:
Q8WVK7
Gene ID:
348235
Database links:
Entrez Gene: 348235 Human
Entrez Gene: 66140 Mouse
Entrez Gene: 287598 Rat
Entrez Gene: 691962 Rat
SwissProt: Q8WVK7 Human
SwissProt: Q9CR46 Mouse
SwissProt: Q5I0J4 Rat
Unigene: 46727 Human
Unigene: 45008 Mouse
Unigene: 203397 Rat
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