Nuclear mitotic apparatus protein 1 - Q14980 (NUMA1_HUMAN)


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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 (PubMed:7769006, PubMed:17172455, PubMed:19255246, PubMed:24996901, PubMed:26195665, PubMed:27462074). Functions to tether the minus ends of MTs at the spindle poles, which is critical for the establishment and maintenance of the spindle poles (PubMed:12445386, PubMed:11956313). Plays a role in the establishment of the mitotic spindle orientation during metaphase and elongation during anaphase in a dynein-dynactin-dependent manner (PubMed:23870127, PubMed:24109598, PubMed:24996901, PubMed:26765568). 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 (PubMed:23027904, PubMed:22327364, PubMed:23921553). 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 (PubMed:22327364, PubMed:23921553, PubMed:24996901, PubMed:24371089). Binds also to other polyanionic phosphoinositides, such as phosphatidylinositol 3-phosphate (PIP), lysophosphatidic acid (LPA) and phosphatidylinositol triphosphate (PIP3), in vitro (PubMed:24996901, PubMed:24371089). Also required for proper orientation of the mitotic spindle during asymmetric cell divisions (PubMed:21816348). Plays a role in mitotic MT aster assembly (PubMed:11163243, PubMed:11229403, PubMed:12445386). Involved in anastral spindle assembly (PubMed:25657325). Positively regulates TNKS protein localization to spindle poles in mitosis (PubMed:16076287). Highly abundant component of the nuclear matrix where it may serve a non-mitotic structural role, occupies the majority of the nuclear volume (PubMed:10075938). Required for epidermal differentiation and hair follicle morphogenesis. UniProt
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Subunit Structure
Homodimer (PubMed:10075938). Also forms multiarm oligomers by association of C-terminal tail domains, oligomers may further assemble to form a hexagonal nuclear lattice-like network (PubMed:10075938). Associates with the dynein-dynactin complex; this association promotes the transport and accumulation of NUMA1 at the mitotic spindle poles that is inhibited by the BRISC complex in a PLK1-dependent manner (PubMed:10811826, PubMed:17172455, PubMed:23027904, PubMed:22327364, PubMed:26195665). Part of a spindle orientation complex at least composed of GNAI1, GPSM2 and NUMA1 (PubMed:26766442). Interacts (via C-terminus) with microtubules (MTs); this interaction is direct and promotes both MT bundle formation and stability in a dynein-dynactin complex- and CDK1-independent manner (PubMed:12445386, PubMed:11956313, PubMed:26765568). Interacts with EPB41 and EPB41L2; these interactions are negatively regulated by CDK1 during metaphase and are important for anaphase-specific localization of NUMA1 in symmetrically dividing cells (PubMed:23870127, PubMed:24996901). Interacts (via C-terminus) with GPSM2 (via TPR repeats); this interaction is direct, prevented by competitive binding of INSC, is inhibited in a PLK1-dependent manner, blocks the association of NUMA1 with MTs and inhibits NUMA1-induced MT bundle formation, prevents the association of NUMA1 with SPAG5, induces mitotic spindle pole localization of GPSM2, both metaphase cell cortex localization of NUMA1 and mitotic spindle organization (PubMed:11781568, PubMed:12445386, PubMed:22327364, PubMed:24109598, PubMed:27462074, PubMed:21816348). Does not interact with GPSM2 during anaphase (PubMed:23870127). Interacts (via C-terminus) with the nuclear importin alpha/importin beta receptor; this interaction is inhibited by RanGTP (PubMed:11163243). Interacts (via C-terminus) with KPNB1; this interaction is inhibited by RanGTP and the BRISC complex (PubMed:11229403, PubMed:26195665). Interacts with ABRAXAS2 and the BRISC complex; these interactions regulate mitotic spindle assembly (PubMed:26195665). Interacts (via N-terminal end of the coiled-coil domain) with RAE1; this interaction promotes mitotic spindle formation (PubMed:17172455). Interacts (via C-terminus) with SPAG5 (via C-terminus); this interaction promotes the recruitment of SPAG5 to the MTs at spindle poles in a dynein-dynactin-dependent manner and regulates mitotic spindle organization and proper chromosome alignment during mitosis (PubMed:27462074). Interacts with TNKS; this interaction occurs at the onset of mitosis (PubMed:12080061, PubMed:16076287). Interacts with TNKS2 (PubMed:12080061). Interacts with tubulin (PubMed:11956313). UniProt
The C-terminal tubulin-binding domain mediates direct binding to microtubules, independently of dynein-dynactin complex, and induces their bundling and stabilization (PubMed:11956313). The 4.1-binding domain is necessary for its cortical stability and spindle orientation (PubMed:24109598). UniProt
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