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#spindle fibers

14 public questions tagged with this topic.

During mitosis, kinetochore microtubules:

Kinetochore microtubule fibers K fibers dynamic behavior changes across mitotic stages governed by tension sensing checkpoint signaling and motor forces generating chromosome movement. During prometaphase microtubules nucleated at centrosomal poles probe cytoplasm via dynamic instability growth at plus end at several microns per minute capture kinetochore through NDC80 complex forming bundles of 20 to 40 microtubules stabilized by CLASP and formins. Until anaphase kinetochore microtubules continue polymerization at plus end while minus ends depolymerize at poleward flux mediated by kinesin-13

Ref: Cheeseman & Desai, Annu Rev Cell Dev Biol – Kinetochore microtubules polymerize until anaphase then depolymerize.

What happens during prometaphase?

Prometaphase is transitional stage converting interphase nuclear architecture to mitotic spindle structure, initiated by rising cyclin B-CDK1 activity. CDK1 phosphorylates lamins A/C and B at serine residues within tail domain, causing depolymerization of filamentous lamina and fragmentation of nuclear envelope into vesicles merging with endoplasmic reticulum. Condensed chromosomes consisting of two sister chromatids embraced by cohesin are released into cytoplasm. Concurrently, kinetochores assembled at centromeres containing CENP-A nucleosomes fully mature, forming outer plate with KMN netwo

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 17, Prometaphase Events.