Nuclear fusion during yeast mating occurs by a three-step pathway

Correction: Nuclear fusion during yeast mating occurs by a three-step pathway

Microtubule dynamics in the budding yeast mating pathway.

In order for haploid gametes to fuse during fertilization, microtubules (MTs) must generate forces that are sufficient to move the nuclei together. Nuclear movements during fertilization rely on microtubule-associated proteins (MAPs), many of which have been characterized extensively during mitosis. A useful model system to study MT-dependent forces before nuclear fusion, or karyogamy, is the m...

A Role for a Protease in Morphogenic Responses during Yeast Cell Fusion

Cell fusion during yeast mating provides a model for signaling-controlled changes at the cell surface. We identified the AXL1 gene in a screen for genes required for cell fusion in both mating types during mating. AXL1 is a pheromone-inducible gene required for axial bud site selection in haploid yeast and for proteolytic maturation of a-factor. Two other bud site selection genes, RSR1, encodin...

Nuclear congression and membrane fusion: two distinct events in the yeast karyogamy pathway

Karyogamy is the process where haploid nuclei fuse to form a diploid nucleus during yeast mating. We devised a novel genetic screen that identified five new karyogamy (KAR) genes and three new cell fusion (FUS) genes. The kar mutants fell into two classes that represent distinct events in the yeast karyogamy pathway. Class I mutations blocked congression of the nuclei due to cytoplasmic microtu...

KAR5 Encodes a Novel Pheromone-inducible Protein Required for Homotypic Nuclear Fusion

KAR5 is required for membrane fusion during karyogamy, the process of nuclear fusion during yeast mating. To investigate the molecular mechanism of nuclear fusion, we cloned and characterized the KAR5 gene and its product. KAR5 is a nonessential gene, and deletion mutations produce a bilateral defect in the homotypic fusion of yeast nuclei. KAR5 encodes a novel protein that shares similarity wi...