What does Aurora B kinase do?
Aurora B is a mitotic checkpoint kinase that plays a pivotal role in the cell cycle, ensuring correct chromosome segregation and normal progression through mitosis. Aurora B is overexpressed in many types of human cancers, which has made it an attractive target for cancer therapies.
How does Aurora B work?
Aurora B contributes at least three, partly related functions, to the process of bi-orientation: (1) the modulation of microtubule-binding affinity of the kinetochore to allow or prevent maturation of attachments; (2) the regulation of microtubule dynamics by controlling the activity and localization of microtubule- …
How does Aurora B kinase regulate the kinetochore?
Where is Aurora B kinase expressed?
Expression and subcellular localization Specifically, Aurora B localizes to the chromosomes in prophase, the centromere in prometaphase and metaphase, and the central mitotic spindle in anaphase. This localization has been determined by indirect immunofluorescence in mammalian, C. elegans, and Drosophila cells.
What does kinetochore mean?
Definition. The kinetochore is a protein complex assembled on the centromeric region of DNA. It provides the major attachement point for the spindle microtubules during mitotic or meiotic division to pull the chromosomes apart.
Where can you find Aurora A and Aurora B during mitosis?
centrosome
AIP1 localises at the centrosome where it binds and downregulates Aurora A early in mitosis [20]. Full activation of both Auroras requires binding to specific protein cofactors.
How many kinetochores are there?
46 chromosomes are present in a human being. These chromosomes have two kinetochores each. One is allowed for each sister chromatid. Therefore, 92 kinetochores are present in a human during mitosis.
What are the three types of microtubules?
The overall shape of the spindle is framed by three types of spindle microtubules: kinetochore microtubules (green), astral microtubules (blue), and interpolar microtubules (red). Microtubules are a polarized structure containing two distinct ends, the fast growing (plus) end and slow growing (minus) end.
What is the function of Securin?
Securin is also an APC substrate and is known for its role in inactivating the cohesin-cleaving enzyme, separase, until the metaphase to anaphase transition. Here we show that securin has an additional role in cell-cycle regulation, that of modulating the timing of entry into M-phase.
How many centromeres do humans have?
46 centromeres
In a human cell, in late prophase, there would be 46 centromeres visible if the magnification is high enough. Each of the 46 pairs of sister chromatids is held together by a centromere.
What is the function of kinetochores?
In eukaryotes, the kinetochore is a proteinaceous multi-subunit assembly whose main function is to generate load-bearing attachments of sister chromatids (the replicated chromosomes held together by the protein complex cohesin) to spindle microtubules during cell division (mitosis or meiosis) (Figure 1A).
What are three functions of microtubules?
Microtubules are part of the cytoskeleton, a structural network within the cell’s cytoplasm. The roles of the microtubule cytoskeleton include mechanical support, organization of the cytoplasm, transport, motility and chromosome segregation.
What are the components of Aurora B kinase?
Aurora B complexes with three other proteins, Survivin, Borealin and INCENP. Each of the four components of the complex is required for the proper localization and function of the other three. INCENP stimulates Aurora B kinase activity.
How is the activity of Aurora B regulated?
Aurora B kinase (in green) localizes in a cell cycle dependent manner. The expression and activity of Aurora B are regulated according to the cell cycle. Expression of Aurora B reaches a maximum at the G2-M transition, whereas Aurora B protein is most active during mitosis.
What is the role of Aurora B in cancer?
Aurora B is a serine-threonine kinase belonging to the highly conserved Aurora family of mitotic kinases. Aurora B is a chromosomal passenger protein involved in chromosome segregation, spindle-checkpoint, and cytokinesis. Alteration of each of these steps could induce aneuploidy, one of main features, and driving force of cancer progression.
What is the phosphorylation consensus sequence for Aurora B?
Aurora B is a family member of serine/threonine protein kinases (Kimura et al., 1997) and has the preferred phosphorylation consensus sequence as [RK]x [TS] [ILV] (Cheeseman et al., 2002).