Protein: SKA complex subunit 1 (Spindle and kinetochore-associated protein 1) (Q96BD8)
Organism: Homo sapiens (Human)
Function: Component of the SKA1 complex, a microtubule-binding subcomplex of the outer kinetochore that is essential for proper chromosome segregation. Required for timely anaphase onset during mitosis, when chromosomes undergo bipolar attachment on spindle microtubules leading to silencing of the spindle checkpoint. The SKA1 complex is a direct component of the kinetochore-microtubule interface and directly associates with microtubules as oligomeric assemblies. The complex facilitates the processive movement of microspheres along a microtubule in a depolymerization-coupled manner. Affinity for microtubules is synergistically enhanced in the presence of the ndc-80 complex and may allow the ndc-80 complex to track depolymerizing microtubules. In the complex, it mediates the interaction with microtubules.
Subcellular location: Cytoplasm, cytoskeleton, spindle {ECO:0000269|PubMed:15561729, ECO:0000269|PubMed:24413531, ECO:0000269|PubMed:26981768, ECO:0000269|PubMed:27225956, ECO:0000305|PubMed:29487209}. Chromosome, centromere, kinetochore {ECO:0000269|PubMed:17093495, ECO:0000269|PubMed:22483620, ECO:0000269|PubMed:24413531, ECO:0000269|PubMed:26981768, ECO:0000269|PubMed:28479321}. Cytoplasm, cytoskeleton, microtubule organizing center, centrosome {ECO:0000269|PubMed:19646878}. Note=Localizes to bioriented kinetochores and spindle microtubules during metaphase in a NDC80 complex-dependent manner (PubMed:17093495, PubMed:28479321, PubMed:29487209). The SKA complex begins to concentrate at kinetochores before microtubule attachment but reaches maximum levels on bioriented metaphase chromosomes (PubMed:17093495). Localizes both to microtubule plus-ends and along the length of microtubules (PubMed:27225956). The localization of the SKA complex to kinetochores is positively regulated by protein serine/threonine kinase CDK1 (PubMed:28479321). The localization of the SKA complex to kinetochores is negatively regulated by protein serine/threonine kinase AURKB, and this action is opposed directly or indirectly by the PP1 and PP2A protein phosphatase complexes (PubMed:22371557, PubMed:27697923). Localizes at the centrosome during interphase and prophase (PubMed:19646878). Localizes to the meiotic spindle, but not to kinetochores, from the stage of germinal vesicle breakdown (GVBD) to meiosis II (MII) (By similarity). {ECO:0000250|UniProtKB:Q9CPV1, ECO:0000269|PubMed:17093495, ECO:0000269|PubMed:19646878, ECO:0000269|PubMed:22371557, ECO:0000269|PubMed:27225956, ECO:0000269|PubMed:27697923, ECO:0000269|PubMed:28479321, ECO:0000269|PubMed:29487209}.
Interaction partners:
- Spindle and kinetochore-associated protein 2
- Spindle and kinetochore-associated protein 3
- Kinetochore protein NDC80 homolog
- Mitotic checkpoint serine/threonine-protein kinase BUB1 beta
- Centromere protein F
- Protein Spindly
- Kinetochore protein Nuf2
- Serine/threonine-protein kinase PLK1
- Cell division cycle protein 20 homolog
- Biorientation of chromosomes in cell division protein 1
Sequence:
MASSDLEQLCSHVNEKIGNIKKTLSLRNCGQEPTLKTVLNKIGDEIIVINELLNKLELEIQYQEQTNNSLKELCESLEEDYKDIEHLKENVPSHLPQVTVTQSCVKGSDLDPEEPIKVEEPEPVKKPPKEQRSIKEMPFITCDEFNGVPSYMKSRLTYNQINDVIKEINKAVISKYKILHQPKKSMNSVTRNLYHRFIDEETKDTKGRYFIVEADIKEFTTLKADKKFHVLLNILRHCRRLSEVRGGGLTRYVIT