Microtubules born on microtubules

Microtubule (MT) arrays form, say Janson et al. (page 297), when MT nucleators stick to existing MTs. This creates new nucleation sites for more MTs, thanks to the activities of γ-tubulin and a MT-associated protein called mto2p.Fission yeast have a simple, consistent interphase MT arrangement composed of four bundles per cell. The two antiparallel MTs that make up each bundle overlap at their minus ends at the interphase microtubule organizing center (iMTOC), which attaches to the nuclear envelope.

The nuclear envelope is also where mto2p has been found. The new results suggest that mto2p organizes interphase MTs by recruiting a complex of γ-tubulin and its associated proteins (γ-TuC) to existing MTs. mto2p colocalized with γ-TuCs on MTs, particularly at iMTOCs. It was at these colocalization...