Nuclear fusion in the yeast Saccharomyces cerevisiae.

Karyogamy, or nuclear fusion, is the process during mating by which two haploid yeast nuclei fuse to produce a single diploid nucleus. Karyogamy occurs in two major steps: microtubule-dependent nuclear congression followed by fusion of the nuclear envelope membranes. Many of the proteins required for karyogamy have been discovered to act in related processes during mitotic growth. Accordingly, yeast karyogamy has become an important model system to investigate critical functions of the cytoplasmic microtubules and the microtubule organizing center, the nuclear envelope, and the endoplasmic reticulum.