The mating pheromone, α-factor, of the yeast Saccharomyces cerevisiae binds to the heterotrimeric G protein-coupled cell surface receptor of MATa cells and induces cellular responses necessary for mating. In higher eukaryotic cells, many hormones and growth factors rapidly mobilize a second messenger, Ca2+, by means of receptor-G protein signaling. Although striking similarities between the mechanisms of the receptor-G protein signaling in yeast and higher eukaryotes have long been known, it is still uncertain whether the pheromone rapidly mobilizes Ca2+ necessary for early events of the pheromone response. Here we reexamine this problem using sensitive methods for detecting Ca2+ fluxes and mobilization, and find no evidence that there is rapid Ca2+ influx leading to a rapid increase in the cytosolic free Ca2+ concentration. In addition, the yeast PLC1 deletion mutant lacking phosphoinositide-specific phospholipase C, a key enzyme for generating Ca2+ signals in higher eukaryotic cells, responds normally to the pheromone. These findings suggest that the receptor-G protein signaling does not utilize Ca2+ as a second messenger in the early stage of the pheromone response pathway. Since the receptor-G protein signaling does stimulate Ca2+ influx after early events have finished and this stimulation is essential for late events in the pheromone response pathway Ca2+ may be used only once in the signal transduction pathway in unicellular eukaryotes such as yeast.
CITATION STYLE
Nakajima-Shimada, J., Sakaguchi, S., Tsuji, F. I., Anraku, Y., & Iida, H. (2000). Ca2+ signal is generated only once in the mating pheromone response pathway in Saccharomyces cerevisiae. Cell Structure and Function, 25(2), 125–131. https://doi.org/10.1247/csf.25.125
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