Related Experiment Video
Updated: Aug 5, 2026
05:35
Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins
Published on: March 3, 2016
Structure and function of the outer kinetochore
Andrea Musacchio1,2, Pim J Huis In 't Veld3,4, Rae R Brown5
1Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany. Andrea.Musacchio@mpi-dortmund.mpg.de.
Nature Reviews. Molecular Cell Biology
|August 3, 2026
Summary
The kinetochore, a molecular machine, ensures accurate chromosome segregation during cell division. Its core complex (KMN) binds microtubules, regulating cell cycle progression and chromosome alignment.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The kinetochore is a crucial molecular machine responsible for chromosome segregation.
- It consists of inner and outer regions, with the outer kinetochore mediating microtubule binding and mitotic progression control.
- The Knl1-Mis12-Ndc80 (KMN) complex forms the core of the outer kinetochore.
Purpose of the Study:
- To elucidate how the KMN complex achieves accurate regulation of chromosome segregation.
- To explain the dynamic integration of activities at microtubule-binding sites.
- To review the function of the KMN complex in mitotic progression and the spindle assembly checkpoint.
Main Methods:
- Live-cell imaging of chromosome alignment during mitosis.
- Biochemical reconstitution of kinetochore components.
- High-resolution structural analyses.
Main Results:
- The KMN complex directly binds microtubules.
- It recruits additional microtubule binders and modulators.
- It acts as the primary switch for the spindle assembly checkpoint.
Conclusions:
- The KMN complex plays a central role in accurate chromosome segregation.
- Understanding its function is key to comprehending mitotic progression and cell cycle control.
- Further research combines live-cell imaging, biochemistry, and structural biology to reveal its mechanisms.
Related Concept Videos
02:57Attachment of Sister Chromatids
As cells progress into mitosis, the nuclear envelope breaks down, and the condensed chromosomes are exposed to the array of bipolar microtubules of the mitotic spindle. The kinetochore, a large, disc-shaped protein complex, is present at the centromere region of the sister chromatids and acts as a binding site for the microtubules. Usually, the plus-end of a single microtubule is embedded within the kinetochore. However, some kinetochores first establish lateral contact with the side-wall of a...
02:27The Mitotic Spindle
The mitotic spindle—or spindle apparatus—is a eukaryotic, cytoskeletal structure made up of long protein fibers called microtubules. Formed during cell division, the spindle separates sister chromatids and moves them to opposite ends of a parental cell, where the now individual chromosomes are distributed to two daughter cell nuclei.
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
02:27The Mitotic Spindle
The mitotic spindle—or spindle apparatus—is a eukaryotic, cytoskeletal structure made up of long protein fibers called microtubules. Formed during cell division, the spindle separates sister chromatids and moves them to opposite ends of a parental cell, where the now individual chromosomes are distributed to two daughter cell nuclei.
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
02:11Forces Acting on Chromosomes
During mitosis, chromosome movements occur through the interplay of multiple piconewton level forces. In prometaphase, these forces help in chromosome assembly or congression at the equatorial plane, eventually leading to their alignment at the metaphase plate. The forces acting on the chromosomes are space and time-dependent; therefore, they vary with the position of the chromosomes as the cell progresses through mitosis.
Microtubules and motor proteins exert two types of forces on...
Microtubules and motor proteins exert two types of forces on...
02:50Spindle Assembly
Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
01:24Microtubules in Cell Motility
Microtubules are thick hollow cylindrical proteins that help form the cytoskeleton. Microtubules have varied roles in the cell. These filaments help form cellular appendages like cilia and flagella, which are responsible for locomotion. The cilia arise from basal bodies, separated from the main body by a membrane-like structure forming the transition zone. This zone is the gate for the entry of lipids and proteins, creating a unique composition of lipids and proteins in the ciliary membrane and...