Related Experiment Video
Updated: May 22, 2026

Heterokaryon Technique for Analysis of Cell Type-specific Localization
Published on: March 11, 2011
Subcellular localization and role of Ran1 in Tetrahymena thermophila amitotic macronucleus
Haixia Liang1, Jing Xu, Dan Zhao
1Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China.
Abstract:
Amitosis, a direct method of cell division is common in ciliated protozoan, fungi and some animal and plant cells. During amitosis, intranuclear microtubules are reorganized into specified arrays which assist in separation of nucleus, despite lack of a bipolar spindle. However, the regulation of amitosis is not understood. Here, we focused on the localization and role of mitotic spindle assembly regulator: Ran GTPase (Ran1) in macronuclear amitosis in binucleated protozoan Tetrahymena thermophila. HA-tagged Ran1 was localized in the macronucleus throughout the cell cycle of Tetrahymena during vegetative growth, and the accessory factor binding domains of Ran1 contributed to its macronuclear localization. Incomplete somatic knockout of RAN1 resulted in aberrant intramacronuclear microtubule array formation, missegregation of macronuclear chromosomes and ultimately blocked macronuclei proliferation. When the Ran1 cycle was perturbed by overexpression of Ran1T25N (GDP-bound Ran1-mimetic) or Ran1Q70L (GTP-bound Ran1-mimetic), intramacronuclear microtubule assembly was inhibited or multi-micronucleate cells formed. These results suggest that Ran GTPase pathway is involved in assembly of a specialized intramacronuclear microtubule network and coordinates amitotic progression in Tetrahymena.
Related Concept Videos
Directionality of Nuclear Transport
The Nucleolus
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Additional Subnuclear Structures
The nucleus contains many membrane-less subnuclear organelles or nuclear bodies, such as nucleoli, Cajal bodies, speckles, paraspeckles, etc. These nuclear...
Nuclear Protein Sorting
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Nuclear Localization Signals and Import

