Current Perspectives on Saccharomyces cerevisiae Sphingolipids

This review focuses on recent advances in our understanding of sphingolipid functions in Saccharomyces cerevisiae, particularly their role in signal transduction. The sphingoid long-chain bases, dihydrosphingosine and phytosphingosine, have gained prominence in yeast as regulators of the AGC-type protein kinase Pkh1 and Pkh2, homologs of mammalian phosphoinositide-dependent protein kinase 1 (PDK1). Pkh1 and Pkh2 activate the downstream kinases Pkc1, Ypk1, Ypk2 and Sch9. In addition, PHS acts downstream of Pkh1 and partially activates Ypk1, Ypk2 and Sch9. These kinases control a wide range of cellular processes including growth, cell wall integrity, stress resistance, endocytosis and aging. Our appreciation of long-chain bases as second messengers will grow as we learn more about the processes controlled by AGC kinases as well as other yeast kinases that are likely to be regulated by long-chain bases.