Miranda Is Required for the Asymmetric Localization of Prospero during Mitosis in Drosophila

Asymmetric division of Drosophila neuroblasts, sensory organ precursor cells, and cells in the procephalic neurogenic region involves the segregation of Numb and Prospero proteins into one of the two daughter cells. We have isolated a novel gene, miranda, based on the ability of its gene product to interact with the Prospero asymmetric localization domain. miranda expression coincides spatially and temporally with asymmetric cell divisions and asymmetric localization of Prospero. Miranda protein is localized asymmetrically, along with Prospero, to the basal cell membrane during mitosis. Loss of miranda gene function abolishes asymmetric Prospero localization during mitosis. The asymmetric localization of Miranda protein requires inscuteable. Our results suggest that miranda functions downstream of inscuteable and works as an adapter that connects Prospero to the basal cell membrane during asymmetric cell division.