The Iml3 protein of the budding yeast is required for the prevention of precocious sister chromatid separation in meiosis I and for sister chromatid disjunction in meiosis II.

The mitotic kinetochore of the budding yeast contains a number of proteins which are required for chromosome transmission but are non-essential for vegetative growth. We show that one such protein, Iml3, is essential for meiosis, in that the absence of this protein results in reduced spore viability, precocious sister chromatid segregation of artificial and natural chromosomes in meiosis I and chromosome non-disjunction in meiosis II.