Cell extensions in pkc1 mutants of Saccharomyces cerevisiae

To obtain information on cell wall synthesis and its relationship to morpho logy, we examined the induction of cell extensions of yeast upon the additi on of isoamyl alcohol in osmotically fragile mutants that had mutations in es related to the cell integrity pathway through activation of the mitogen- activated protein kinase cascade. We found that isoamyl alcohol induces cel l extensions in pkc1 deletion mutants but not in mutants with mutations in genes positioned downstream or upstream of the PKC1 gene. These results sug gest that Pkc1p functions not only in the integrity pathway but also in the induction. We characterized the elongated cells; many had two or more nucl ei. We found no difference in cell surface structure between round and elon gated cells from the results of chitin staining and cell wall extraction. A ctin cytoskeleton was organized in elongated cells, as well as round cells. Cytochalasin D (0.08 mg/mL) inhibited the formation of actin cable but did not affect the induction of cell extensions.