Localized secretion of acid phosphatase reflects the pattern of cell surface growth in saccharomyces cerevisiae

Abstract

Secretion of cell wall-bound acid phosphatase by S. cerevisiae occurs along a restricted portion of the cell surface. Acid phosphatase activity produced during derepressed synthesis on a phosphate-limited growth medium is detected with an enzyme-specific stain, and is localized initially to the bud portion of a dividing cell. After 2-3 generations of phosphate-limited growth, most of the cells can be stained; if further phosphatase synthesis is repressed by growth in excess phosphate, dividing cells are produced in which the parent, but not the bud, can be stained. Budding growth is interrupted in a-mating-cells by a pheromone (.alpha.-factor) secreted by the opposite mating type; cell surface growth continues in the presence of .alpha.-factor and produces a characteristic cell tip. When acid phosphatase synthesis is initiated during .alpha.-factor treatment, only the cell tip can be stained; when phosphatase synthesis is repressed during .alpha.-factor treatment, the cell body but not the tip can be stained. A mixture of derepressed a cells and phosphatase-negative .alpha. cells form zygotes in which mainly one parent cell surface can be stained. The cell cycle mutant, cdc 24 (Hartwell) fails to bud and, instead, expands symmetrically as a sphere at a nonpermissive temperature (37.degree. C). This mutant does not form a cell tip during .alpha.-factor treatment at 37.degree. C, and although acid phosphatase secretion occurs at this temperature, it is not localized. Secretion may reflect a polar model of yeast cell-surface growth, and this organization may require the cdc 24 gene product.