A. Sil et I. Herskowitz, IDENTIFICATION OF AN ASYMMETRICALLY LOCALIZED DETERMINANT, ASH1P, REQUIRED FOR LINEAGE-SPECIFIC TRANSCRIPTION OF THE YEAST HO GENE, Cell, 84(5), 1996, pp. 711-722
S. cerevisiae cells exhibit asymmetric determination of cell fate. Cel
l division yields a mother cell, which is competent to transcribe the
HO gene and switch mating type, and a daughter cell, which is not. We
have isolated a mutant in which daughters transcribe HO and switch mat
ing type. This mutation defines the ASH1 gene (asymmetric synthesis of
HO). Deletion and overexpression of ASH1 cause reciprocal cell fate t
ransformations: in ash1 Delta strains, daughters switch mating type as
efficiently as mothers. Conversely, overexpression of ASH1 inhibits s
witching in mother cells. Ash1p has a zinc finger motif related to tho
se of GATA transcriptional regulators. Ash1p is localized to the daugh
ter nucleus in cells that have undergone nuclear division. Thus, Ash1p
is a cell fate determinant that is asymmetrically localized to the da
ughter nucleus where it inhibits HO transcription.