Microtubule (MT)-binding protein that plays a role in the formation and maintenance of the spindle poles and the alignement and the segregation of chromosomes during mitotic cell division (  , ). Functions to tether the minus ends of MTs at the spindle poles, which is critical for the establishment and maintenance of the spindle poles (, ). Plays a role in the establishment of the mitotic spindle orientation during metaphase and elongation during anaphase in a dynein-dynactin-dependent manner ( , ). In metaphase, part of a ternary complex composed of GPSM2 and G(i) alpha proteins, that regulates the recruitment and anchorage of the dynein-dynactin complex in the mitotic cell cortex regions situated above the two spindle poles, and hence regulates the correct oritentation of the mitotic spindle ( ). During anaphase, mediates the recruitment and accumulation of the dynein-dynactin complex at the cell membrane of the polar cortical region through direct association with phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), and hence participates in the regulation of the spindle elongation and chromosome segregation ( , ). Binds also to other polyanionic phosphoinositides, such as phosphatidylinositol 3-phosphate (PIP), lysophosphatidic acid (LPA) and phosphatidylinositol triphosphate (PIP3), in vitro (, ). Also required for proper orientation of the mitotic spindle during asymmetric cell divisions . Plays a role in mitotic MT aster assembly ( ). Involved in anastral spindle assembly . Positively regulates TNKS protein localization to spindle poles in mitosis . Highly abundant component of the nuclear matrix where it may serve a non-mitotic structural role, occupies the majority of the nuclear volume . Required for epidermal differentiation and hair follicle morphogenesis (By similarity).
Subcellular locations: Nucleus, Nucleus, Nucleoplasm, Nucleus matrix, Chromosome, Cytoplasm, Cytoskeleton, Cytoplasm, Cytoskeleton, Microtubule organizing center, Centrosome, Cytoplasm, Cytoskeleton, Spindle pole, Cytoplasm, Cell cortex, Cell membrane, Lateral cell membrane
Mitotic cell cycle-dependent shuttling protein that relocalizes from the interphase nucleus to the spindle poles and cell cortex (, ). The localization to the spindle poles is regulated by AAAS . In interphase, resides in the nuclear matrix ( ). In prophase, restricted to the interchromatin or condensed chromosome space . In prometaphase, after nuclear envelope disassembly, forms aggregates both in the spindle midzone and at duplicated centrosomes and astral microtubules (MTs) of the bipolar spindle apparatus . Translocates from the spindle midzone towards the spindle poles along spindle fibers in a MT- and dynein-dynactin-dependent manner until the anaphase onset (, ). In metaphase, recruited to the polar cortical region in a GPSM2- and GNAI1-dependent manner ( ). Excluded from the metaphase equatorial cortical region in a RanGTP-dependent manner (, ). Phosphorylation on Thr-2055 by CDK1 results in its localization at spindle poles in metaphase, but not at the cell cortex . In anaphase, recruited and anchored at the cell membrane of the polar cortical region in a EPB41-, EPB41L2-, phosphatidylinositol-dependent and GPSM2- and G(i) alpha proteins-independent manner ( , ). Excluded from the anaphase equatorial region of the cell cortex in a RACGAP1- and KIF23-dependent and RanGTP-independent manner . Associated with astral MTs emanating from the spindle poles during anaphase (, ). Nonphosphorylated Thr-2055 localizes at the cell cortex, weakly during metaphase and more prominently during anaphase in a phosphatase PPP2CA-dependent manner . As mitosis progresses it reassociates with telophase chromosomes very early during nuclear reformation, before substantial accumulation of lamins on chromosomal surfaces is evident . Localizes to the tips of cortical MTs in prometaphase . Localizes along MTs and specifically to both MT plus and minus ends . Accumulates also at MT tips near the cell periphery . Colocalizes with GPSM2 at mitotic spindle poles during mitosis (, ). Colocalizes with SPAG5 at mitotic spindle at prometaphase and at mitotic spindle poles at metaphase and anaphase . Colocalizes with ABRO1 at mitotic spindle poles . Colocalized with TNKS from prophase through to anaphase in mitosis . Colocalizes with tubulin alpha . CCSAP is essential for its centrosomal localization . In horizontally retinal progenitor dividing cells, localized to the lateral cortical region (By similarity).
Subcellular locations: Cytoplasm, Cytosol, Cytoplasm, Cytoskeleton, Microtubule organizing center, Centrosome, Cytoplasm, Cytoskeleton, Spindle pole
During interphase, mainly clustered at the centrosomal region in the cytosol. After entry into mitosis, detected at mitotic spindle poles.
Subcellular locations: Cytoplasm, Cytosol, Cytoplasm, Cytoskeleton, Microtubule organizing center, Centrosome, Cytoplasm, Cytoskeleton, Spindle pole
During interphase, mainly clustered at the centrosomal region in the cytosol. After entry into mitosis, detected at mitotic spindle poles.