Section 7
Chapter 6,847

Tubulin nucleation and assembly in mitotic cells: evidence for nucleic acids in kinetochores and centrosomes

Pepper, D.A.; Brinkley, B.R.

Cell Motility 1(1): 1-15


ISSN/ISBN: 0271-6585
PMID: 6184168
DOI: 10.1002/cm.970010102
Accession: 006846276

A lysed cell system was used to study the organelle structure and nucleation of exogenous tubulin at kinetochores and centrosomes in mitotic PtK2 cells. This lysed cell system was used in conjunction with nuclease digestion experiments to determine which specific nucleic acids (DNA or RNA) are involved in either the structure and/or microtubule-initiating capacity of kinetochores and centrosomes. DNase I appears to specifically decondense the kinetochore plate structure, with the eventual loss in the ability of the chromosomes to nucleate microtubule assembly. DNase I had no effect on either the structure or nucleating capacity of centrosomes. Both RNase T1 and RNase A specifically attacked the amorphous pericentriolar material of the centrosomes, with a concomitant loss in the ability of this material to nucleate microtubule formation. Neither RNase appeared to affect the structure or nucleating capacity of the kinetochore. The 2 types of nucleases appear to exert preferential effects on the different types of microtubule initiation sites in mitotic mammalian cells. DNA is evidently a major component to the kinetochore, while RNA is a major component of the amorphous pericentriolar material. Microtubule initiation sites in mitotic cells may contain nucleic acids which are essential for the structural and functional integrity of the sites.

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