Fig. 2

Hypothetical representation of the functions performed by the γ-tubulin meshwork during interphase and mitosis. In interphase, the meshwork is composed of centrosomes, γ-tubules, and γ-strings. The nuclear and the cytosolic pool of γ-tubulin are connected with γ-strings across the nuclear envelope. γ-tubules regulate the concentration of the cytosolic pool of γ-tubulin. The γ-tubulin meshwork changes in a cell-cycle-dependent manner. In prophase, the nuclear envelope is dispersed. γ-tubulin accumulates in the pericentriolar region of the centrosomes and assists in formation of the mitotic spindle. The number of γ-tubules is reduced in mitotic cells (prophase, metaphase, anaphase, and telophase). During mitosis, the centrosomes coordinate the segregation of chromatids between the newborn cells through orientation and organization of the mitotic spindle. The dispersed components of the nuclear envelope localize to the mitotic spindle and cell periphery. In anaphase/telophase, the components of the nuclear envelope nucleate at the γ-tubulin boundary. At the end of mitosis, the nuclear envelope is formed, and the γ-string bridges are reestablished