Abstract
Microtubules are the ubiquitous components of eukaryotic cells and are organized around specific cellular structures referred as “microtubule-organizing centers” (MTOCs). This chapter describes the functional components of MTOCs. Three types of MTOCs are found in all cell types: (1) centrosome, or equivalent structure, which organizes the cytoplasmic microtubule array of interphase cells, (2) spindle poles, which organize the microtubules of the spindle apparatus, and (3) kinetochores, which are specialized regions at which chromosomes attach to the microtubules of the spindle apparatus. MTOCs of plants are usually associated with membranous structures, such as the nuclear envelope, the plasma membrane, and membrane-bound vesicles. During interphase, a single centrosome serves as the focal point for most of the microtubules of the cytoskeleton. A centrosome is composed of a cloud of electron-dense material, which, in animal cells, is usually associated with a pair of centrioles. The fundamental properties of MTOCs include the nucleation, orientation, and anchoring of microtubules. In addition, MTOCs affect not only the frequency with which microtubules nucleate but also determine the structure of the assembled microtubules.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1-50 |
| Number of pages | 50 |
| Journal | International Review of Cytology |
| Volume | 136 |
| Issue number | C |
| DOIs | |
| State | Published - Jan 1 1992 |
Bibliographical note
Funding Information:We thank Drs. W. E. Theurkauf and R. S. Hawley for providing us with a copy of their manuscript prior to publication, and Drs. J. V. Kilmartin, S. Doxsey, and J. L. Salisbury for allowing us to include their unpublished results in this article. We also thank Drs. M. E. Porter and T. S. Hayes for their careful reading of the manuscript and helpful suggestions for revision, Drs. A. L. Khodjakov and T. Maekawa for their suggestions in the preparation of the diagrams shown in Figs. 1 and 2, and MI. Jerry Sedgewick for reproduction of these figures. The work described here from the authors’ laboratory was supported by NIH research grant GM41350 to RK. MK was supported on an NIH fellowship, GM13062.