How Is Daughter-Specific Localization Achieved?
In a series of elegant experiments, Mazanka et al. [5] also addressed exactly when Ace2 enters the daughter cell nucleus during the cell cycle. Using time lapse microscopy, they demonstrated that the Cbk1–Ace2 complex localizes to the daughter cell nucleus prior to cytokinesis. This result is quite surprising, as at this stage proteins are able to freely move between the mother and daughter cells, and suggests the existence of an active mechanism that restricts nuclear accumulation of the complex to daughter cells. In addition, they used a double mutant strain affecting both orientation of the mitotic spindle and checkpoint control, such that both nuclei frequently accumulate in one cell, either the mother or daughter. This experiment shows that the environment of the daughter cell is essential for nuclear accumulation of Ace2. What is unique about the daughter cell that allows Ace2 to accumulate in the nucleus? Cbk1 localizes first at the tip of the incipient bud of the daughter cell,
