Microtubule nucleation is the process in which several tubulin molecules interact to form a microtubule seed. Microtubule nucleation occurs spontaneously in purified tubulin solutions, and molecular intermediates between tubulin dimers and microtubules have been identified. Microtubule nucleation is enhanced in tubulin solutions by the addition of gamma-tubulin or various gamma-tubulin complexes. In vivo, microtubule assembly is usually seeded by gamma-tubulin ring complexes. Recent studies suggest, however, that microtubule nucleation can occur in the absence of gamma-tubulin, and that gamma-tubulin may have other cell functions apart from being a major component of the gamma-tubulin ring complex.
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http://dx.doi.org/10.1016/s0955-0674(02)00003-0 | DOI Listing |
J Cell Biol
March 2025
State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China.
TPX2 is an elongated molecule containing multiple α-helical repeats. It stabilizes microtubules (MTs), promotes MT nucleation, and is essential for spindle assembly. However, the molecular basis of how TPX2 performs these functions remains elusive.
View Article and Find Full Text PDFiScience
January 2025
Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
Cancers and neurodegenerative disorders are associated with both disrupted proteostasis and altered nuclear morphology. Determining if changes in nuclear morphology contribute to pathology requires an understanding of the underlying mechanisms, which are difficult to elucidate in cells where pleiotropic effects of altering proteostasis might indirectly influence nuclear morphology. To investigate direct effects, we studied nuclei assembled in egg extract where potentially confounding effects of transcription, translation, cell cycle progression, and actin dynamics are absent.
View Article and Find Full Text PDFSSNA-1 is a fibrillar protein localized at the area where dynamic microtubule remodeling occurs including centrosomes. Despite the important activities of SSNA1 to microtubules such as nucleation, co-polymerization, and lattice sharing microtubule branching, the underlying molecular mechanism have remained unclear due to a lack of structural information. Here, we determined the cryo-EM structure of SSNA-1 at 4.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Biochemistry and Molecular Biology, Frederick P. Whiddon College of Medicine, Mobile, AL 36688, USA.
An intracellular protozoan, the Apicomplexan parasite () infects nucleated cells, in which it triggers the formation of a specialized membrane-confined cytoplasmic vacuole, named the parasitophorous vacuole (PV). One of the most prominent events in the parasite's intracellular life is the congregation of the host cell mitochondria around the PV. However, the significance of this event has remained largely unsolved since the parasite itself possesses a functional mitochondrion, which is essential for its replication.
View Article and Find Full Text PDFBiomedicines
December 2024
A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
The changes in the level of small GTPase ARL4C are associated with the initiation and progression of many different cancers. The content of ARL4C varies greatly between different tissues, and the induction of ARL4C expression leads to changes in cell morphology and proliferation. Although ARL4C can bind alpha-tubulin and affect intracellular transport, the role of ARL4C in the functioning of the tubulin cytoskeleton remained unclear.
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